I have  completed the "Leader of The Pack" achievement and have found that i did not unlock the achievement. I then completed another achievement (Zombie Doctor) and unlocking it on my PlayStation account. I then checked my Minecraft character to see that it said that i had not completed the achievement. This is also the same with every achievement that I have unlocked that has reward and I have not gotten a single reward. 

Ps. Sorry I do not know the version I am on but i know that it is the latest out saying it is version 2.20 on my PlayStation but it did not give me an option