So when playstation 4 finally got realms, I started my own servers and I now have friends from xbox one and ps4 on the realm but we have found a few bugs some big and some small. 

1. Every so often all players (including me) gets kicked out of the realm and it always goes back to the last back up save. 
2. Some times mobs turn up invisible and unable to damage them. 
3. After being on the realm for a bit of time the realm starts to lag out (mobs moving slow etc.)
4. Sometimes when placing blocks they just disappear (causing deaths).