I had a problem printing 1099-NEC as well.  I was able to print 1099-MISC.  The rep I had at Quickbooks  was able to isolate and solve the problem.  She had me run a back up of my QB file, then:

Click HELP

Click Update QB Desktop

Click Update Now folder (not the blue box)

Click Reset Update box

Click Get Updates

I then had to close QB and re-open it.

I am now busily printing 1099-NEC for each of my clients.