When the player is controlling a Character actor, using the CharacterMovementComponent (CMC), unexpected movement corrections will occur while standing still on a movement base that is rotating.
Critical steps to reproduce: have a large rotating movement base
I reproduced this by modifying QAGame's TM-CharacterMovement test map in this manner:
Find the section of the map that has 4 moving platforms set up to behave differently.
Find the platform that is rotation-only.
Scale the platform to be slightly larger, so it's easier for clients to jump onto it reliably.
Reduce its Rotation amount to be less, like 0.1 or so. This will slow down the spinning speed, making it easier to test.
Enter this in the command console: p.NetShowCorrections 1
In Editor Prefs, turn on Enable Network Emulation. Any low-latency situation should work.
Run PIE as a Client
Jump onto the rotating platform and stand still.
Observe periodic or steady corrections occurring (debug capsules will appear) while not moving. These will be more frequent if you are far away from the center of the platform, and may even go away if you're close to it.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-166232 in the post.