403 error for students trying to view prezis

I’ve encountered a major issue with all my prezi presentations. I created my presentations 6 years ago and have been using them every semester since then with no issues. About 2 weeks ago my students began letting me know that they can no longer access the presentations (403 error message). I have 360 students who need access to my presentations. Please help.

A post was split to a new topic: Prezi Classic 403 issue

A post was split to a new topic: 403 Prezi Classic issue

A post was split to a new topic: 403 Classic error

A post was split to a new topic: Classic 403 error