I had the same problem in my game two weeks ago. Many players complained that the anti-cheat system - which relies on the server seeing the player’s correct position - was being falsely triggered at random, with no clear pattern.
I disabled ImprovedPhysicsReplication, and I haven’t received any complaints about it since.
I am still having significant problems in my hockey game similar to what @iogician described above.
The puck is an unanchored part that has a server script that essentially sets the network owner to the closest player. Whilst changing owners, there is a significant jitter/pause when this happens. See the example videos below. The green O over players’ heads denotes that they have network ownership of the puck.
after re-enabling the update, my game is still unfortunately experiencing some very strange behavior on network ownership changes as well.
Hi, thanks for bringing it up again.
We are actively working on this bug now, will ping you for retry after it’s fixed.
We won’t remove the “Disabled” option before all the bugs are fixed.
Thanks!
Great, thanks for the quick response.
Hi all, we are actively resolving the remaining issues.
The disabled option will remain available until all bugs are fully addressed. Once the fixes are deployed, we will update this post and provide a two-week validation window for everyone to test and verify the changes
Experiencing weird player stuttering where it appears as if players are lagging/stuttering, but you’re not locally.
Stuttery/Jittery movement even with decent ping and stable network?
A clue is that I have an idle animation on.
I only notice it on more full servers (ours goes upto 67 players), on private servers with lower number counts its fine.
Hey, please consider the replies others are sending here, I’ve had awful experiences with this system, from breaking other peoples creations to ruining my own place.
The physics chokes badly on my end and yeah, this system also seems to re-introduce the infamous old ancient ROBLOX bug of hinges (or in this case hinge constraints) just starting to randomly fling objects/cars/etc off the map. (Old devs/players that were around for this know exactly what i’m talking about).
Edit; I will also say, it seems like this eventually also crashes the server after it continues choking badly for a period of time.
I’ve had multiple friends reach out asking me “wat happened” turning out that the server just dies, stops responding. I guess after a couple of minutes the disconnection message will appear but it’s in some strange zombified stuck state where it takes awhile, and so players are just stuck, scripts quit working and all that.
I have made a bug report that is caused by this with detailed (and relatively simple) replication steps here.
Posting in this thread as per suggestion to try to get this looked at 
We have fixed at least one bug around this and also have a few more pending fixes. It’s probably better to test this as a whole again once all fixes are deployed. We’ll update the post once it’s ready.
Hi, thanks for the report. If you have an repro file, I am happy to take look.
Generally speaking, there are a couple of known issues around stuttering, and we are working on them. I think it makes sense to retest the system once all the fixes are deployed. And we’ll update the post once the fixes are ready.
I’ll take a look, thanks for the bug report!
@Send_Scripts
Hi, we’ve rolled out a fix for the ownership change issue. Can you try enable ImprovedPhysicsReplication again and let us know if the original reported issue is fixed or not?
@Iogician @TrojanHorseAttack
Hi, we’ve rolled out a fix for the ownership change issue. Can you try enable ImprovedPhysicsReplication again and let us know if the original reported issue is fixed or not?