Mask Path not working properly

[Trevor324681291gcn]

I'm trying to use the mask path in premier for a stop motion project. I was able to successfully use it at first, but now it has this weird issue where it will leave behind my previous mask when I go to the next image in the sequence. I've tried everything to fix this, but nothing works. I attached a video so you can better see what I'm talking about. Any suggestions on how to fix? 

[Ann Bens · Accepted solution]

Nest your clips then add the mask.

[Byron Cortez · Accepted solution]

The mask will affect only the clip to which you have applied it. If you have multiple clips and want a mask to affect all clips, you must nest the clips and then apply the mask on the nested sequence. 

Select all the clips you want to nest, right click and choose the nested sequence option. Then apply the mascara.