Thanks for your response.
I did use the censor in the lower left throughout the clip & only one clip. The black square in the center was not there before I saved my clip. It only appeared on the clip after I had saved it. I might have accidentally caused this error but at the time I could not figure out why or how.
The original clip is just a few minutes & had 3 edits so I decided to redo it. This time I used the Censor effect first then did my edits & after saving did not see the black square.