Clip resizes upon delivery

Hello all, new to resolve and editing in general. I have a project I’m working on where I’m using some split screen by resizing the clips and then putting a mask over top to make nice defined lines between school screen. Everything looks good in the edit but when I go to deliver and start the render some of the clips resize to seemingly random sizes and block out much of the screen. It looks terrible. What’s happening?! Help!

[Peter Chamberlain]

In the project settings, check that the Image sizing, Output sizing is set to timeline, and dont change the output sizing on the deliver page. Does that help?