Echoing this problem. Same version and OS. This started happening since updating to this version. I do not know what the previous version was.
This happens roughly 80% of the time when performing the following actions:
Refreshing the branch explorer
Syncing
Checking in
Switching changesets/branches
Fortunately I have not been hamstrung by this like @Xarbrough. There are instances when the performed action will not take place when this modal appears, but I'm able to fix it by performing the action again. A reinstall did not work for me. However, the frequency of the modals increased after the reinstall.