Hello there @alyssar44,
hope you’re doing well today! ??
I imported your settings in a testing site of mine where I was using only Hustle and TwentyNineteen theme and I was able to close the pop-up with the X icon.
https://monosnap.com/file/1iZWnsVV7gFbw2ldojIwUdzgFjMoNu
This means that there should be some kind of conflict that causes that. Could you please proceed with a conflict test to narrow this down?
First, create a recent backup in case you lose any settings during the test and have to restore to a previous working state.
Then deactivate all plugins and MU-plugins apart from Hustle, activate a default theme like TwentyNineteen, clear all caches and check again if the issue is still there. If not, it means that something is conflicting, so start activating the remaining plugins and theme, one by one this time, checking every time for the reported issue, until you reproduce the issue, thus finding the conflicted combination. The following flowchart image can assist you during this test: https://premium.wpmudev.org/wp-content/uploads/2015/09/Support-Process-Support-Process.gif
If this is a live website with traffic, I’d rather advise to create a staging environment, meaning a complete and exact copy of this installation into another location/folder in the same server, using a separate database, and perform the test in there instead without worrying about the live site.
Looking forward to your results!
Thank you,
Dimitris