Action changes active screen automatically constantly

[Good_Punk]

I'm trying to record old DOS games in DosBOX. I have two monitors setup. Now Action constantly changes the active screen from my main monitor to my secondary monitor during recording.
I guess it's related to changing resolution or something, but I'm recording at fix 1080p so that shouldn't be an issue.

I would love to have an option to lock the active screen so that Action - no matter what - doesn't change the active monitor by itself.