Firefox for Mac 72.0.1 prints only 3 pages of a web page. There seems to be a problem with Print Preview or Apple's Preview application or both, their interaction.
I've tried all of the suggestions. I tried all the print options. I tried using the Print Edit extension. I disabled extensions. I used safe mode. I tried deleting all the Preview prefs. I tried deleting every trace of Firefox and Mozilla from my hard drive, then reinstalling Firefox. I deleted and reinstalled my printer drivers for a monochrome Brother laser printer HLL 2370 that is only a few months old. I'm running macOS 10.11.6
Web pages print correctly in Brave, Safari, and iCab. Therefore this is a problem with Firefox. It's a perennial problem that I have had for many years. I have ALWAYS had problems printing web pages in Firefox. It's always something. I don't understand how something so basic can continue to go unfixed when other browsers don't have a problem with it. I'm baffled by the whole thing.
- User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:72.0) Gecko/20100101 Firefox/72.0
Yes, that issue baffles me too, since the first day I started using Firefox in Aug 2002, when it was called Phoenix.
Try using this extension: https://addons.mozilla.org/en-US/firefox/addon/printable-the-print-doctor/
Works for me on Windows, hope it works as good on MacOSX.
Thanks for the fresh suggestion. But it didn't work.