Gremlins have moved into my Indesign

In your account of the troubleshooting steps you took you never mentioned trashing your InDesign preferences. This process resets the program to its defaults and along with Peter's suggestion will, hopefully, get all of your InDesign versions working correctly.

To do so on a Mac:

The User Library folder in which InDesign’s preferences are stored is hidden by default on most Macintoshes. To access it make sure that InDesign is closed and click on the desktop to launch a Finder Window (Command-N). With this window in column view follow the path User>Home folder (it’s the folder with an icon that looks like a house—it may have the user’s name rather than “Home”) and click on the Home folder. With the Option Key pressed choose Library from the Finder Go Menu. “Library” will now appear within the Home folder. Within the Library folder find the folder called Preferences and within it find the folder called “Adobe InDesign” and the file called “com.adobe.InDesign.plist” and delete both that folder and that file. When InDesign is next launched it will create new preference files and the program will be restored to its defaults.

The advantage of manually deleting preference files in this manner is that after you’ve reset up the program (make sure that no document window is open) to your liking, you can create copies of your personalized “mint” preference files (make sure that you quit the program before copying them—that finalizes your customization) and use them in the future to replace any corrupt versions you may need to delete.

Sounds like a document corruption, that's why it's always important to save incrementally name copies so you can revert to an earlier version should this occur.

Try and save a copy as an IDML version to clear out the crud that builds up and open it again as a new InDesign document to see if that resolves the issue.