Just posting this in case anybody is having this same issue with the ZWO 2600MC using APT. Error attached.
I constantly kept getting a "Can't read the image" message in APT although it wasn't consistent. Today I've done a bunch of testing (cables, ports, hubs etc) and in the end the only thing that has worked is using the ASCOM driver instead of using the ZWO native driver, so far(although I wouldn't bet money on it yet) I haven't had an issue.
Please let me know if anyone has found a different solution to this.