As a further update: Last night also started out fine, and then went south after 03:30 UTC. It is strange that the issue always seems to happen later in the observing run after several successful focus runs have happened. I caught it in the act, so to speak, last night and opened the C:\Users\xxxx\Documents\FocusMax V4\Images folder. I could see the little 24K focus images saving, and then being overwritten by the next one without a hitch. I saw a larger pImage file get written as well, but it disappeared a short time later. I can't imagine what's happening, but FM4 obviously is capable of writing to the folder.

I have disabled the Return Slew feature for tonight, but I am not the one on the system tonight. In addition, last night there were also failures at the beginning of some focus runs, so the return slew is somewhat moot. My hope, however, is that with the return slew turned off, the focus run will not register as a failure and cause the whole process to repeat again after the next image. From 03:30 to the end of the night, there was a focus attempt and failure after every frame. More than half the total time was spent trying to get a successful focus.

I can send more logs Ė Both ACP and FM4 Ė if it will be helpful.

Also, to the best of my knowledge, the only changes to the system over the past 2 weeks or so have been the beta FM4s Iíve installed.