Compressor 4.2 under El Capitan

Something strange: Monitor screen in compressor is yellow (without motion picture), but it doesn‘t affect on encoded file, fortunately.

I'm not seeing that behavior. Also not seeing the screen shot.

Start by going into Preferences > Advanced > Reset Queue. There choose to Cancel Job, and Repair Compressor. Then run the Update Droplets function, even if you don't have any.

I also have strange yellow shapes in FCPX on some places.

1. On timeline , over place where is transition but only in lower region over waveform.
2. On preview monitor over places where are overlay commands for factory fx plugins.

Same here with Compressor and Cinemagraph PRO

There is an issue with Core Image some developers have mentioned to me. It is cosmetic, or should only be cosmetic. As long as the final encoded file looks fine. Compressor hasn't been officially updated to EC yet, so keep that in mind, also.