Hi. Seems that r200611_win64 stops the "turn off monitor" power saving feature from working. Previous r200601_win64 was OK.
I'm not aware of any changes in Avidemux code which might have any influence on power saving. Probably a new bug/feature of Qt, which was updated for MinGW builds from 5.12.0 to 5.15.0. Qt is still at 5.12.5 in VC++ builds, so if the VC++ build doesn't wake up the display, Qt should be at fault. Else please provide more details (which activity of Avidemux interrupts the idle state of the session?).