You're right in the sense that ankle locks are definitely gone, I know they didn't get carried over. Leg locks are definitely in the game, those are easy to pull off
I just did some research an apparently the only way for heel hooks to show is the person needs to be stunned while entering stacked guard. So not just moving to stacked guard, they need to be stunned too
So that would explain why nobody seems to be really using them, they require a very specific situation where they'll actually show
Top comment on
this thread outlines how this guy has gotten them to show more consistently, but seems only useful to career, as I don't even know what fighters have a heel hook assigned.
Overall, seems like they just implemented heel hooks poorly
EDIT: And yeah, kneebars and ankles locks are gone, along with a slew of other submissions:
Kneebar
Peruvian necktie
Japanese necktie
Omoplata
Gogoplata
Americana
Twister
Winshield choke
North-south choke
Bulldog choke
Anaconda choke
Inverted triangle
And these are just on the top of my head