Mega_Spud, thanks for the update and that works fine but when we nametag something then log out and come back in the name is removed. Will make another post about this.
My minecarts also despawn and they are in a 1 by 6 area to catch all the goodies from my watermelon and pumpkin farms. I had to completely redesign my farms which have prove to be less rewarding.
Do you have the option turned on in your settings?
Same thing in my realm, when I name a mob and when I log out and then back in the mob is no longer named.
I have experienced an issue like this as well. I will try to remove someone from my realm and when I go back it will have a different person kicked.
I have spent many hours fishing and have not caught one name tag. Same as OP, I will get a "null" catch every once in awhile. Looking forward to this getting corrected.
This is still happening in version 1.2.9. Just got done with my enderman farm but it is not working due to enderman not attacking endermites.