Clip jumps after resizing.

I work on a PC and premiere pro 2019. I am working with 1024 x 540 proxy footag from a 4K shoot. When I zoom in to get a better close up and or add a dissolve to a clip resized the clip flickers even after I rendor it. Even it a set to frame size the clip sometimes still flickers back and forth. 

What am I doing wroung?