InCopy randomly doesn't save checked-in changes

InCopy randomly don't save changes after checking in and closing the document. Sometimes, when I open the document again straight away, the changes are still there, but when my colleague opens the same document a few hours later, all the changes have been reversed. So far, I have seen no pattern to when the changes stick and when they don't.

Is there anything I can do about this? I'm far from an InCopy expert, I only use it to make minor changes to laid out text. I'm using version 13.1 x64.

I couldn't find any previous threads with this exact problem, but if there are I'd be grateful if you could point me at them

Cheers,

Kat