They still flee and despawn, even after breeding. The "Trusting" tag is never set to 1b.
I can't seem to add any additional affected versions (it says "No Matches" for anything I type,) but I know it affects 20w15a and earlier.
Had a flower generate inside a house in 1.16.1. Seed 3269460958352272665, position 126 70 239.
Just had this happen with a witch on 1.14.4 multiplayer server. The witch was in a minecart I was chasing after into unloaded chunks. There's an activator rail to empty the cart at the station. As I approached the station, I saw the witch for a second, and then she vanished.
Edit: The witch mysteriously reappeared later.
Confirmed 19w11b, Survival mode.
The issue includes bred ocelots and their offspring. I've also had a similar issue with donkeys, but it's more sporadic, and I haven't confirmed for 1.16.