Area Effect Clouds flicker, even with proper tick speed

If you summon an AEC 20 times per second with a commandblock or function, and the name is visible, instead of staying contentiously in the air, the name flickers back and forth. This causes it to be horribly readable.

Reproduction:

1. Open a new world
2. Put a commandblock with summon area_effect_cloud ~ ~1 ~ {CustomName:"\"Test\"",CustomNameVisible:1} in it
3. Let it run on non-redstone, repeat
4. The name will be readable, but very unstable and flickering all the time.

 

This is not caused by tick lag, as it works in any world.Is this a bug, or something new? Or is there already another issue like this?