cell doesnt complete during commandline call?

I was running some code through papermill commandline interface and noticed on my output notebooks that some cells look incomplete. The cell in question (above) takes a little long (maybe an hour). I was wondering if maybe there's a timeout setting for a cell or something, or did the cell run completely but just didn't render correctly?
What version of papermill , nbconvert and jupyter_client do you have installed? There was a known issue with older versions where messages could overflow and get lost, though it was hard to trigger.
There's no inherent timeout set for cell execution (we have cells that run for days sometimes). Is the issue reproducible or occurred just once?