blur effect mask

[#1]

When you add a blur effect to a video in Premiere Pro 14.6 and set the area with a mask, both ends of the video are deleted.

[#2]

When you add a blur effect to a video in Premiere Pro 14.6 and set the area with a mask, both ends of the video are deleted.

[#3]

It's not clear what you mean, can you share a screenshot?