Existing villagers don't follow updated trading mechanics

Existing villagers don't follow the new increased trading rules before lock out. However, newly bred villagers do - so you end up with newly bred villagers trading for <=16 times before lockout whereas villagers that existed before the update will trade for <= 6 times before lockout. Have tried breaking/replacing workstations and beds with no success.

NOTE: The new rules are brilliant however and many many thanks!!!

Steps to Reproduce:

1. Create a world in 1.14.60
2. Spawn a villager and give him a profession
3. Open the world in 1.16
4. Trade with the villager 6 times