Masking

I'm working on a music video using premiere 2019, I'm using masks to transition to different shots, I have key frames the positioning of the masks, for some reason when the masks move they turn translucent. My opacity is set to 100% and I've found that the only to fix it is by turning the feathering to zero. Which makes no sense, and I need a feather. I'm not sure if it's just a preview or something either, I've never had this issue.