Thanks for the reply and suggestions!
I’m testing in PIE where Listen Server and Client are on the same system, but this is also happening in builds where I’m playing with another person on a different system. And locally, it happens regardless if the Client’s window is focused or not. It definitely appears to be a replication/server correction issue.
I set up a debug key to print what the Server says is the Player Character’s owner and then what the Client says is the owner, and I did find that there was a different answer! I corrected that, but it didn’t resolve the issue.
I did find that turning off the Character’s Replicate Movement stopped the jitter, but it also caused other issues.