Endermen won't attack Endermite [20w12a]

So, for a map I'm making, I've set doMobSpawning to false, and I'm trying to create an Enderman farm using Endermites. I'm aware that Endermen will only attack a natural, pearl-spawned Endermite usually, but found via the Wiki that they have an NBT tag (namely, PlayerSpawned) that, when they have a value of 1, will allow Endermen to attack it.

Here's my issue; it's not working. I've tried 1 and 1b (since that is the only thing that will work on most occasions) and even tried my luck with 0 and 0b, but no dice. I can't spawn an Endermite naturally because of doMobSpawning being false.

Is this PlayerSpawned NBT thing bugged, and should I submit a report seeing this is a snapshot version? Or is there something else I'm missing here?

After doing some testing, I've found it's a line-of-sight issue with the Endermen. Apparently my Endermite was just one block above their sight, so they didn't actually see the Endermite at all.