Thanks Daryl. Not sure what happened, but I unpublished all customizations, deleted the customization, re-imported it, then Published with Cleanup. Now I am able to access the Adobe Preferences screen.
One other thing I did differently when importing, next to Choose File, the Browse button is no longer available in the Modern UI, but if you click the empty space with the file type it’s looking for (in this case *.zip), it does allow you to browse. OR, you can drag a file into this the box with *.zip. I tried both ways, but the final time I dragged the file into that import screen. It seems odd, but I’ve received errors trying to import a snapshot when I browse for the snapshot, but it works fine when I drag a file instead.
Not sure if dragging the file fixed my issue, but since that seems to avoid errors with other import screens in the Modern UI, I’ll definitely be dragging all my files instead of “browsing” for them.