When I use an include mask, I get a white rectangle in my final image

[Andy]

I want to control which image is used in a certain overlap area. I can add a "mask" polygon and change it to "include", but all it does is /exclude/ every other overlapping image - so I get a white rectangle. The area I specified to include is not included. What could I be doing wrong?

[Andy]

Never mind. I had two overlapping "include" areas on different images, so everything was excluded there. (I forgot I had "include" areas on other photos.) For anyone else browsing an answer to this question, if you get white areas you don't understand, check that you haven't asked to "include" that area from two source images.