I think we've seen the same behavior here. Are your clients running Win10 & using print as PDF? We haven't found a root cause yet, but something appears to be mishandling the hand-off between Acrobat Reader & IE. We see the acrobat process spin up when the print tab pops open in IE, but nothing ever displays. However - refreshing (F5) the grey tab will display the document and the print dialog will pop.
Now...if the original tab is left open (or another document that was printed), additional documents can be printed without issue, but as soon as all the documents in the print tabs are closed, the Acrobat process spins down and the same grey tab appears in IE for the next print attempt.
Chrome & Firefox don't exhibit the issue as they appear to be using their own PDF engine, so no interaction with Acrobat Reader is happening. That's my theory anyway. I don't think this is a DW issue - I have heard reports of a similar problem between a couple other internal products, but have not observed the issue there.