That does not seem like a bug in ffmpeg.
If there are 15 frames @25 fps (=1 frame plays 40ms) the correct play length is 600ms.
Only way to get more would be if the source is vfr or not properly flagged.
Ahhh,... I see the problem.
The last frame has a duration of 24s 960ms which is the missing difference. (so the source is vfr)
In case this is properly recorded in the time codes, enabling "Config->Automation->On Load->Always extract timecodes from intput" (and disabling the 'only some') might help.
This effect might also happen if there is an addition stream that is 25s 560ms long.
Iirc there was a change in ffmpeg that it properly stops decoding if there are no additional frames. Older versions returned the last frame over and over again until the length was archived.
-> this is not a bug in Hybrid and personally I wouldn't even call it a but in ffmpeg.
https://superuser.com/questions/1439924/...est-stream sounds similar to your issue.
Cu Selur