Masks do not render properly at all!

This issue is getting incredibly frustrating, especially since I have a deadline to meet soon.

The issue is fairly simple, I have some scenes masked off to color-correct specific areas of the scene (to be more specific, to blacken out disruptions on a black background) but when rendered out it just gets incredibly screwed up. One of the masks just doesn't show up at all, and the other blackens out the ENTIRE frame instead of being confined to the mask. Keep in mind I set these both up in the EXACT same way (masked off in fusion and then darkened in the Color tab)
Everything looks perfect in the timeline, but it just gets broken after rendering (MP4, H.264 in case you were wondering). Is there a setting that somehow screws it up upon exporting? Which obscure box do I need to tick after digging through 3 menus?

I've attached some screenshots that show one of the masks functioning properly in the timeline, but disappearing after rendering.

I'm not an expert on masks, but I'd recommend masking and darkening in Color. (Or in Fusion, but not in a combination of the two.)

Color can track adjustment masks and if it's where you're adjusting, I'd stick with that. You might also find it's Qualifiers work better than tracking masks, but I don't totally understand your task.

If it's a simple darken, you could also do this entirely in Fusion, but Color is simpler. (Resolve was originally built on Color and Color is sophisticated enough to track elements, do keying, etc, all by itself.)

Are you charging timeline size in rendering?

Hi there,

The pics didn't help me to see your issue but anyway, I think I understood what you wanted to achieve... And things I'd suggest are :
- finish the whole operation in the same tab you started it. If you make a power window in color, just track and blacken there. Same recommendation in Fusion (where I would do it), mask, track and cover there entirely ;
- Focus on the potential changes of resolution/sizes or framerates between what you cut and what you export. There are chances your masks are somewhere else in the frame, and/or have drifted from one time to another due to TC changes ;
- similar option : masks (polylines) in Fusion are defaulted to auto-keyframe. Say you created one which is ok at frame x but for some reason you (deliberately or not) modified it at frame z, it will interpolate from one to the other and the full frame darkened may be connected to a problem like that