Root motion allowing rotation client arbitrary desync in 5.1, but happening since 5.0EA

Hi!

I wanted to flag an ongoing issue that happens over time in multiplayer sessions in 5.1 and has been happening for 2-3 years in 5.0EA, 5.0 etc


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Allowing root motion rotations can desync server/client locations. It happens in around 5% of spawned AIs under exactly the same conditions.
The more time you are in a multiplayer session, the more likely you will see this type of teleport behaviour due to server-client desynchronization.
You can see in this video (playing as client) how one of the enemies stopped replicating its server location and teleports right after the montage ended. Then server corrects the real position.

If an AI root motion works on a client, it won’t fail over time. And if an AI desyncs, it won’t get back to normal ever again.

Any clues why this could be happening?

Thanks!