The most possible reason why you're unable to print 1099 is because of the browser error. You'll want to login through an incognito window and print it from there.
Google Chrome: Ctrl + Shift + N
Safari 11 or newer: ⌘ + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Microsoft Edge: Ctrl + Shift + P
Also, let's clear the cache since it causes issues in QuickBooks Online. Lastly, make sure that the browser is up-to-date.
I've included these links for your reference on how to prepare and file your 1099s with QuickBooks Online: