Indeterminate Open End Anchors

Hello,

I’m observing a problem in the master compatibility view as in the screenshot. How can I solve this problem? I tried every way but couldn’t delete these anchors.

Version: G3.1.1

Probably the masters are empty.

I’ve got something similar. After a restart of the App it was gone. But find two empty layers in the Layers Window…? Don’t know what it was… Maybe i’ve added once some additional Masters wich i didn’t used and deleted again…