I would check first in server side Event Viewer, if there are errors in Dynamics/Commerce-RetailServer folder, related to receipts, right after the attempt to print.
It may direct to the real reason.
If there are no errors, then try to clear the Cloud POS's application cache.
Ctrl-F5 could help to do it.
Or may be do it first, then look for errors on server side, if no luck with cache.