Rw crashes upon editing Prefix

Using the latest version (7.2), I am unable to edit (add, delete or edit) anything in Header > Prefix. As soon as I attempt to, Rw gives me the beachball. This happens regardless of the project I’m working with, and whether or not there is already code in the prefix. I filed a bug report, but haven’t heard back yet - so I figured I’d ask here if anyone else is seeing this, or if it’s limited to my Mac. I’m actually uploading identical sites to sixty (yes, 60!) subdomains…and really need to edit the code. If I have to, doing so via FTP will not be fun.