Confirmed for 1.14.4.
Actually, I think maybe if I separate the armor stand into two armor stands, one that controls the movement and one that shows the visuals, and make the visuals have NoGravity, that might work. It'd probably be a lot less smooth, but it's worth it.
I tired playing around with the NoGravity tag to update the armor stand, and it seemed to work, however the armor stand I want to rotate doesn't have NoGravity, and it can't even have it temporarily because it's constantly moving.
Never mind, that doesn't work at all. I still need help.
That's true, but you can't really reopen the world or give it time to fix itself in a map. Also, I eventually found a fairly decent fix myself; Whenever you rotate the armor stand, wait one tick then rotate it slightly, then wait 3 ticks and rotate it back. It should work 100% of the time, hopefully.
Does anyone know of a fix for this? I'm really lost.
Still valid. Hoping this gets fixed soon.