Link/Map IDs just... disappeared.
Hi all -
I'm using RH HTML 9 to maintain our help file, and I've come into a fairly big (okay, devastating) issue with our map files. The issue is that they are just... gone. All my topics were correctly linked yesterday, but when I opened up RH today the links were gone from the Topic Properties menu and I am unable to add/link new IDs:

I'm not quite sure what would have caused this, as the file location hasn't changed and I haven't done anything other than generate a new version of the project. Anyone have any ideas?
I'm not well-versed in the behind-the-scenes workings of RH, so I'm not quite sure what to do here. Please help!
Thanks,
Erin
