Last night I had issues with the Alignment module. This has always been one of the most trouble free modules in my setup.
I did a successful alignment and then started my schedule. When I started the scheduler it did its alignment and failed with "Please check you have sufficient stars in the image, the indicated FOV is correct, and the necessary index files are installed. Enable Alignment Logging in Setup Tab -> Logs to get detailed information on the failure." The image it had taken looked fine with many stars. After a few attempts I got it to work again (not really clear why). I ran the scheduler and all was OK until the meridian flip when it again failed to align with the same message. Its exactly the same same setup I have been using all season with success. Has anything changed in the last update that might cause this?
An option was recently added to help with this sort of issue. If you enable this option then when you get the problem you will have the file and can try plate solving it later and / or post it to the forum...
Be aware as per the tooltip that you probably don't want the option permanently enabled for disk space reasons.
For me the message about Check for "sufficient stars" is always about having BIG stars in the image that will not accept the selection box and are ignored.
I cannot claim this answer, but Hy assisted and suggested that the problem is about having BIG Stars and he suggested I inflate the Max MultiStar HFR from the default of 4.50 pixels to say 10 pixels.
So on the Guide Options Configure box -> Other Settings -> SEP Multistar (recommended) I change Max HFR to 10 pixels - Thanks Hy.