Good day, as a normal player, i have been building a XP farm, enderman one, specifically. Ive put nametag on my endermite (spawned by enderpearl) and then i have forced it to get inside a minecart, like normal players most of the time do. After a while, the endermite despawned, even tho it was named by the nametag. 

Some misc info: height of farm 60 blocks (endermen take 42 block fall damage)
The farm is around 180 blocks far from the obsidian platform, in the main End dimension island.
Hope you have a good day and that the bug does not take long to fix , with a big thanks, Samuel.