Digital Editions deleted highlighting and notes

I have been using digital editions for a couple of weeks to read a book, highlight in it, and take notes. It was downloaded as a loan from a university library, which only allowed me to view the book in its entirely in digital editions - I could not download it as a seperate PDF. When I opened it this evening, all of my work had disappeared - all highlighting, notes and bookmarks are gone. The book had not been deleted or re-downloaded. No changes at all to how I was using things. This was all for a dissertation so I am understandably quite upset that my work is gone. I was initially told by support that digital editions is old (helpful...) and that potentially, attempting to open the file in acrobat would resolve this issue and save me many hours of redoing my work. However I have already tried to open the file both on acrobat and reader, and simply receive the message 'The security plug-in required by this command is unavailable.'

I have spent an hour and a half being passed to 4 support team members about this, so any help would be greatly appreciated! I have tried older tips I found for solving the issue (such as highlighting something new to bring up the old again) but with no  result.