Losing my mind trying to figure out cropping

[purple24]

My preview window is not an accurate depiction of what the crop tool actually does. I have created a custom split screen setup using a Photoshop image as the template, then cropping my video tracks to taste under and above. Looks fine in Premiere, but when I export I have coloured horizontal lines from my template image showing. I also don't understand how this is even happening because the length of these lines aren't even consistent from right to left. I have no other effects going on, no feathering or whatever. Any pointers appreciated.

Also, just to be clear, no funny business going on in my export. All the settings are correct and consistent with the source footage (square pixels, etc)

[Mo Moolla]

Please post screenshots or vids of what the finals look like

[purple24]

Managed to fix the problem by using a colour matte over it (worth noting I'm probably creating my split screens in a fairly idiosyncratic way). Will do more tests tonight however and post screenshots if I run into more problems.