Hello @DeanC
Thank you for reaching out on the community and telling us about your issue. I do apologize for the issue you're having. Does this happen while you try to open the file? Does it allow you inside the file but continually keep asking for you to sign in? It sounds like it's just not detecting your account sign in so we could sign out/sign in but I'm not sure if that's an option.
Once you get the chance could you let us know the answers to a couple of those questions and we'll see what we can do to get your file opened again.
Thanks,
Quicken Francisco