outputs of jupyter notebooks spontaneously cleared

Lately, every once in a while the cell outputs in some of the jupyter notebooks in my project just get deleted 
I haven't been able to link it to any particular action 
This happens while I'm not working in any of these notebooks (not using jupyter at all), I don't have a jupeter server running (in pycharm or out of it)
It seems to happen in a few, but not all notebooks, all at once, I can't find a pattern yet
My current theory is that some refactor operation is causing this in notebooks that contain the refactored symbol, but I'm not able to reproduce this

Anyone else run into this?