What happens if you just click the link normally?

Another user reported that links open a new tab and then Firefox immediately closes them. Definitely unusual behavior. Is that what happens on yours?

https://support.mozilla.org/questions/1200914

Sometimes a blocker blocks too much.

Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

My problem is the same as Question 1200914 linked above. Disabling add-ons fixed the problem and re-enabling them brought it back. Unclicking 'use hardware acceleration' in Performance preferences didn't work. Starting in safe mode didn't work. I see the other person fixed it by rebooting his OS so I'll see if that works. Thanks to both of you!

Sometimes a uBlock filter goes wrong. You could try "force updating" them. This was the first thing that came up in a search for that: https://www.reddit.com/r/uBlockOrigin/comments/6nklqw/how_do_i_force_an_update/

At this point I'm going to put up with the minor inconvenience of using right-click and see if the problem eventually resolves itself. Thanks again.

ublock does not work on mail.google.com .

Disable it!

After I disabled it on https://mail.google.com/ then everything works again.

Hi rickrich, if you want to re-enable it, there's a recent thread with the developer about how to fix the problem here:

https://www.reddit.com/r/uBlockOrigin/comments/7ryy4p/ublock_has_started_blocking_popups_from_gmail/