Armor Stands are not updating their rotation when being teleported with rotation values.
Test:
1. Summon armor stand
2. Don't teleport armor stand in x y z directions: /tp @e[type=ArmorStand] ~ ~ ~ ~20 ~
3. Armor stand does not turn visually despite multiple runs of the command.
4. One way to update the rotation is by teleporting them in any x y z direction: /tp @e[type=ArmorStand] ~ ~1 ~
Linked issues
Comments 5
This bug is client-side, e.g. the server knows the position is updated (save & exit, reload world, AS displays in updated position)
Duplicate of MC-96821
Roy Sajima that is incorrect. It is not a duplicate

Seems to be related and caused by the same bug though as MC-96821.
With this bug, a key and widely used feature for Animated NPCs and general entity usage is broken.