Editor crashes when duplicating a map (4.21.0)

I tried duplicating a map for our project, but the editor keeps crashing at 50%. We are using git if that changes anything.
See the attached file for crash info. Got any help or recommendation on what i can do?

link text

Hello,

We’ve recently made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.

https://epicsupport.force.com/unrealengine/s/

Thanks