Using sidereal instead of solar tracking rate isn't your problem.
It sounds like you may not be tracking at all, but that depends on what you mean when you say "I have never been able to have it track and keep the sun in view for more than about 30 seconds."
Do you mean the sun completely exits the FOV in that time (how big is the FOV?), or that it drifts noticeably in that time?
There are 86,400 seconds in a mean solar day [24 hr * 60 min/hr * 60 sec/min]. Sidereal days are 86,164 seconds long [~236 seconds shorter].
Sidereal tracking rate = 360° / 86164 sec = 0.0041781°/sec.
Solar tracking rate = 360° / 86400 sec = 0.0041667°/sec
Difference over 30 sec:
Delta = 30 sec (0.0041781 °/sec - 0.0041667 °/sec) = 30 sec (1.14x10-5) °/sec = 3.42x10-4 ° = 0.2 arcmin.
That's probably detectable only with careful study.
Anyhow, in 30 seconds, 0.0041667°/sec (mean solar rate) amounts to:
A = 30 sec * 0.0041667 °/sec = 0.125° = 7.5 arcmin. That fits the rule of thumb for tracking rate, which is one degree per 4 minutes.
Even if tracking is off, that still seems like it might be too slow to be responsible if the problem is the sun drifting more than its own apparent size in that time.
I'm not familiar with the Evo, but, as the first step, are you sure it's tracking at all? Here are some ways to test:
Set it up for solar as you normally do, see if the problem is there, then slew to some distant fixed terrestrial object, remove the solar filter, and see if it moves or doesn't move in the FOV.
If you can't do that, can you leave the scope set up and running as you're using it for solar until night, remove the solar filter, and see if it tracks anything celestial at all? If it's not tracking, this may be immediately apparent since it will still be pointing where you left it if tracking is off!
Alternatively, if you're doing a solar system align on the sun during the day, try doing a solar system align on a planet in the evening (Venus is a good choice at the moment), and test nighttime tracking on that. [Is there even such a thing as "Solar System Align" on the Evo as there is on Celestron GEMs?]
Edited by SkipW, 27 March 2020 - 12:58 PM.