This might be a long shot, but here goes.
I help manage a website that uses the Real3DFlipbook plugin for quite a few digital magazine issues. Just yesterday, we noticed that the back-end editor for the plugin wasn't functioning properly. It doesn't seem to open completely, so we can't upload new Flipbooks, nor can we edit existing ones.
Existing Flipbooks are still viewable on the front-end of the website.
No other website functionality appears to be affected on the back-end or front-end. Articles, Posts and other content taxonomies are still behaving normally.
Additionally, we use Real3DFlipbook on a number of other websites, and we aren't experiencing the same issue on those websites. They are all fine. So, silver lining is it appears to be isolated to this one website.
Has anyone else had this issue with Real3DFlipbook? Or any general insights into how any plugin might behave this way?