Himetsuno

Can you describe the issue a little more and provide screenshots? Are you trying to break blocks in creative and its not working? Also, is the server modded that you are trying to  break blocks on?

keep in mind the original code for both mobs regardless of the fact that they are on the same team. alongside skeletons and untamed wolves which exhibited the same behavior despite being on the same team. being on the same team only alters a small set of code. keep testing it and see if you may find anymore examples. Im curious. 

thats really scary, does this happen everytime you open the game? you may try uninstalling the launcher and reinstalling it

If I am correct, it will only work as a decorative block while you are in creative, try switching gamemodes and see if that helps. 

did you uninstall and reinstall the launcher or Java itself?- updating java may help fix this

Remove the mods (resource, texture) packs and try the command to bring up debug again- it may be because you are using secondary software