Resizing bug

Hi @Angelo375686691896, 

Welcome to the Premiere Pro forums and sorry you've been experiencing issues. We need a few more details to help, like macOS version and hardware specs. Please see How to Report a Problem. 

Does this continue to happen if you try opening different clips in the Source monitor? What if you reset or switch your workspace, unstack the panel, or close and re-open the panel or project? 

Are you using any external monitors or displays? 

Sorry for the frustration, 
Dani