inCopy content suddenly deleted

I am working on a big project with several authors. These authors enter the text via inCopy. Yesterday I open the inDesign document and notice that a text frame suddenly shows no content. I open the inCopy link and it is empty. There is absolutely no text left. The inCopy file was last edited one month before.

Has anyone ever experienced something like this?

If I hadn't made a backup, the content would have been deleted forever.

I am grateful for any advice.