Objects' sleep states are not being properly replicated to the client. While it cant seem to be reliably triggered, occasionally the client will receive a constant stream of sleep events, until the object is awoken again. It is also possible for the client to become permanently awoken and is never put back asleep, regardless of interaction on either the client or server side.
Was not able to repro in 4.20
Create a BP from a cube.
Set it to replicate and replicate movement.
Set it to generate wake events and log when these occur.
Play with at least two players
Result: Occasionally, the client will receive a constant stream of sleep events, until the object is awoken again.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-78122 in the post.