Jukka, I gave your data a whirl. It's not ideal for deconvolution, however pushing the settings about as far as they would go, I was able to get it to deconvolve ok. It is not great, and I would recommend figuring out the tilt and coma in your optical system for sure, as once you have round stars across the field deconvolution will become easier. Anyway. These are the settings I used:

Here is the before and after:

To demonstrate how much getting the settings exactly right, particularly on this kind of data, is critically important. I had to fiddle with the Global Dark setting a lot, and finally got it down to 0.0050. When I did that iteration, I had fewer issues with local divergence, but I still had some:

Deconvolution: Processing preview: drizzle_integration_DBE1_ABE_clone_SHARE->Preview02
Computing CIE Y component: done
Regularized Richardson-Lucy
Iteration 1/40: done
s=1.6903e-004 Ds=+0.0000e+000 sn=6.0560e-006 n=9.6942e-002
Iteration 2/40: done
s=1.6882e-004 Ds=+1.2533e-003 sn=6.0608e-006 n=2.0430e-001
Iteration 3/40: done
s=1.6240e-004 Ds=+3.9536e-002 sn=6.0583e-006 n=1.9228e-001
Iteration 4/40: done
s=1.5893e-004 Ds=+2.1784e-002 sn=6.0614e-006 n=1.9846e-001
Iteration 5/40: done
** Warning: local divergence at iteration #5. Accumulated divergence: 3.491416e-004
s=1.5899e-004 Ds=-3.4914e-004 sn=6.0556e-006 n=2.1678e-001
Iteration 6/40: done
s=1.5621e-004 Ds=+1.7798e-002 sn=6.0532e-006 n=2.0389e-001
Iteration 7/40: done
s=1.5580e-004 Ds=+2.6339e-003 sn=6.0545e-006 n=1.9397e-001
Iteration 8/40: done
s=1.5417e-004 Ds=+1.0545e-002 sn=6.0512e-006 n=1.8884e-001
Iteration 9/40: done
** Warning: local divergence at iteration #9. Accumulated divergence: 2.314460e-004
s=1.5421e-004 Ds=-2.3145e-004 sn=6.0519e-006 n=1.7382e-001
Iteration 10/40: done
s=1.5288e-004 Ds=+8.6616e-003 sn=6.0517e-006 n=1.6645e-001
Iteration 11/40: done
** Warning: local divergence at iteration #11. Accumulated divergence: 2.756877e-004
s=1.5293e-004 Ds=-2.7569e-004 sn=6.0514e-006 n=1.5772e-001
Iteration 12/40: done
s=1.5196e-004 Ds=+6.3594e-003 sn=6.0514e-006 n=1.5393e-001
Iteration 13/40: done
** Warning: local divergence at iteration #13. Accumulated divergence: 1.207746e-004
s=1.5198e-004 Ds=-1.2077e-004 sn=6.0524e-006 n=1.5183e-001
Iteration 14/40: done
s=1.5124e-004 Ds=+4.8806e-003 sn=6.0523e-006 n=1.4942e-001
Iteration 15/40: 83%
<* abort *>

I knocked Global Dark down to 0.0040 after aborting here, and everything worked like a charm, no local divergence and no dark ringing issues:

Deconvolution: Processing preview: drizzle_integration_DBE1_ABE_clone_SHARE->Preview02
Computing CIE Y component: done
Regularized Richardson-Lucy
Iteration 1/40: done
s=3.1080e-004 Ds=+0.0000e+000 sn=6.3793e-006 n=1.9489e-001
Iteration 2/40: done
s=3.0524e-004 Ds=+1.8228e-002 sn=6.3876e-006 n=2.9913e-001
Iteration 3/40: done
s=2.9670e-004 Ds=+2.8784e-002 sn=6.3835e-006 n=2.6360e-001
Iteration 4/40: done
s=2.9154e-004 Ds=+1.7713e-002 sn=6.3785e-006 n=2.6799e-001
Iteration 5/40: done
s=2.9007e-004 Ds=+5.0602e-003 sn=6.3779e-006 n=2.7951e-001
Iteration 6/40: done
s=2.8662e-004 Ds=+1.2047e-002 sn=6.3703e-006 n=2.6492e-001
Iteration 7/40: done
s=2.8522e-004 Ds=+4.8898e-003 sn=6.3747e-006 n=2.5480e-001
Iteration 8/40: done
s=2.8313e-004 Ds=+7.3767e-003 sn=6.3701e-006 n=2.5362e-001
Iteration 9/40: done
s=2.8235e-004 Ds=+2.7662e-003 sn=6.3715e-006 n=2.4472e-001
Iteration 10/40: done
s=2.8093e-004 Ds=+5.0600e-003 sn=6.3700e-006 n=2.4169e-001
Iteration 11/40: done
s=2.8027e-004 Ds=+2.3443e-003 sn=6.3691e-006 n=2.3718e-001
Iteration 12/40: done
s=2.7930e-004 Ds=+3.4786e-003 sn=6.3678e-006 n=2.3504e-001
Iteration 13/40: done
s=2.7874e-004 Ds=+2.0117e-003 sn=6.3667e-006 n=2.3197e-001
Iteration 14/40: done
s=2.7803e-004 Ds=+2.5555e-003 sn=6.3662e-006 n=2.3058e-001
Iteration 15/40: done
s=2.7750e-004 Ds=+1.9070e-003 sn=6.3658e-006 n=2.2758e-001
Iteration 16/40: done
s=2.7696e-004 Ds=+1.9437e-003 sn=6.3650e-006 n=2.2575e-001
Iteration 17/40: done
s=2.7652e-004 Ds=+1.6023e-003 sn=6.3642e-006 n=2.2299e-001
Iteration 18/40: done
s=2.7610e-004 Ds=+1.5181e-003 sn=6.3638e-006 n=2.2078e-001
Iteration 19/40: done
s=2.7573e-004 Ds=+1.3468e-003 sn=6.3631e-006 n=2.1832e-001
Iteration 20/40: done
s=2.7538e-004 Ds=+1.2795e-003 sn=6.3625e-006 n=2.1634e-001
Iteration 21/40: done
s=2.7505e-004 Ds=+1.1708e-003 sn=6.3621e-006 n=2.1451e-001
Iteration 22/40: done
s=2.7468e-004 Ds=+1.3562e-003 sn=6.3620e-006 n=2.1306e-001
Iteration 23/40: done
s=2.7431e-004 Ds=+1.3658e-003 sn=6.3615e-006 n=2.1181e-001
Iteration 24/40: done
s=2.7396e-004 Ds=+1.2843e-003 sn=6.3618e-006 n=2.1073e-001
Iteration 25/40: done
s=2.7363e-004 Ds=+1.1762e-003 sn=6.3605e-006 n=2.0976e-001
Iteration 26/40: done
s=2.7334e-004 Ds=+1.0725e-003 sn=6.3603e-006 n=2.0895e-001
Iteration 27/40: done
s=2.7306e-004 Ds=+1.0363e-003 sn=6.3602e-006 n=2.0812e-001
Iteration 28/40: done
s=2.7276e-004 Ds=+1.0755e-003 sn=6.3598e-006 n=2.0736e-001
Iteration 29/40: done
s=2.7249e-004 Ds=+1.0033e-003 sn=6.3599e-006 n=2.0663e-001
Iteration 30/40: done
s=2.7224e-004 Ds=+9.1432e-004 sn=6.3600e-006 n=2.0600e-001
Iteration 31/40: done
s=2.7201e-004 Ds=+8.3521e-004 sn=6.3597e-006 n=2.0529e-001
Iteration 32/40: done
s=2.7180e-004 Ds=+7.7716e-004 sn=6.3593e-006 n=2.0454e-001
Iteration 33/40: done
s=2.7160e-004 Ds=+7.3375e-004 sn=6.3597e-006 n=2.0374e-001
Iteration 34/40: done
s=2.7142e-004 Ds=+6.8540e-004 sn=6.3592e-006 n=2.0306e-001
Iteration 35/40: done
s=2.7124e-004 Ds=+6.4406e-004 sn=6.3588e-006 n=2.0237e-001
Iteration 36/40: done
s=2.7108e-004 Ds=+6.0946e-004 sn=6.3586e-006 n=2.0168e-001
Iteration 37/40: done
s=2.7092e-004 Ds=+5.7867e-004 sn=6.3584e-006 n=2.0098e-001
Iteration 38/40: done
s=2.7077e-004 Ds=+5.5199e-004 sn=6.3580e-006 n=2.0036e-001
Iteration 39/40: done
s=2.7060e-004 Ds=+6.5003e-004 sn=6.3574e-006 n=1.9969e-001
Iteration 40/40: done
s=2.7042e-004 Ds=+6.6053e-004 sn=6.3566e-006 n=1.9910e-001
Truncating samples: done
Normalizing samples: 0%
Computing extreme sample values: done
Importing CIE Y component: done
6.070 s

So, a tiny change of just -0.001 to Global Dark was enough to get me from non-working settings to working settings. I think with better data...a deeper integration along with rounder stars across the entirety of your field, would make it easier to find working settings. However, sometimes you just have to fiddle to get it working. Also note the regularization settings. I had to push those to the utter limit, as 16 is the max for noise threshold. I had to fiddle with the scaling (and even now, it's not ideal, I may need to bump up some of the protection levels even more to really keep the noise from being affected.)

I have also noticed that you seem to have hot pixels (or something that looks like them) in your data. It appears as though they may be dithered, but they may be low enough in standard deviation that they are not being caught by the clipping algorithm. You might want to run your RAW (before demosaicing) data through CosmeticCorrection (don't forget to check the CFA option!) to identify and eliminate as many hot pixels as you can before demosaicing, registration and integration. You want the cleanest noise profile you can get, as hot pixels or other deviant pixels can sometimes act as loci for deconvolution artifacts (and, for that matter, also as loci for artifacts with registration), and they can limit how far you can push deconvolution.

**Edited by Jon Rista, 20 March 2017 - 12:16 PM.**