Updated to 11.2.0-13 yesterday and didnt do any in combat mounting afterwards.
Today I'm in LFR on an alt and suddenly I can't mount anymore.

Rolled back to 11.2.0-12. Will let you know if it worked.

It was failing with 11.2.0-13 on my hunter.
Rolled back to 11.2.0-12 and it worked on my shaman.
I'll give it another shot with the -13 and try to get u some debug info.

11.2.0-13 worked on my Warrior. Guess my Hunter bugged out in another way.

I'm going to leave this open for a bit. It's entirely possible I have made an error that only shows up some times, so this will give people a place to post it if I have.

Mounting up did not work for me today as well, but I only have one single instance of trying to mount using LiteMount during the Dimensius fight.

What version were you using?

Done it 4 or 5 times now on LFR with 11.2.0-14 and haven't had any failures yet. I have seen other people without any addons complain that the game bugged and they could not mount, but I don't know if that is user error or not.

Closing. Would have been more reports if anything was still broken.