I keep adding mask expansion to masks but they don't do anything

[defaultysazx3fwqvlj]

I am trying to get rounded corners for an image in Premiere Pro. I have added the crop effect and created a mask. The mask selection tool allows me to edit the rounded corners etc. but then nothing happens on playback. I can see the blue corners and can drag around the mask just fine, but it does nothing in the final project. I have searched online and it only seems people have this problem the other way around.

I am very new to premiere pro so I imagine this is something I'm doing wrong as opposed to a fault in the software, but I've tried everything from scratch and followed tutorials but nothing is working. It is infuriating. 

[Ann Bens · Accepted solution]

Dont use the mask feature from the crop effect but rather from opacity.

[Ann Bens]

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