I haven't updated to r390 yet. I updated to r375 a few days ago and have been seeing issues with my custom code functioning. I believe I have narrowed down the cause (or at least what causes things to stop working).
My lighting code consists of 4 scripts: Activity Log, Advanced Smart Lights, Last Event, Stuck Module Check. I have tweaked things a bit since my last upload, but nothing that should cause a complete failure like I'm seeing. It appears that when I have both the Activity Log and Last Event scripts running, Last Event does not run. If I stop Activity Log, Last Event starts functioning again.
The only things of note that have changed recently are updating from r374 and mapping a network drive to the logging file write location. Any thoughts? Were there any changes to the "WhenModuleIsChanging" code?