"Text content is out of date" then "This is not a valid InDesign interface document"

Hi! I'm so bewildered and cannot figure out what to try next. 

I'm working off a shared Dropbox server, and when I go to open an icma file, none of the text is showing up. Each assignment has a yellow triangle with the exclamation point, and when I hover over it, it says "Text content is out of date." If I try to update the text, this message pops up: "This is not a valid InDesign interface document"

I've updated Incopy, restarted my computer, tried turning off synching (and turning it back on) and making the file available offline. I'm on a mac as are my coworkers, who are able to access the assignments just fine. The lovely ppl at the design firm we work with have tried reassigning the files, but it hasn't helped. No one has the file checked out or anything. I'm able to see the rest of the file — images — in the layout view. Any help is GREATLY appreciated!

I'm really not sure what else to do!