I can confirm that this is an issue. A few months ago I also created an R15 morph system which had some issues regarding killing players randomly.
I tried this as well, and it didn’t seem to help out… The issue for me was the first time a player morphed.
I was using a package ID and got the package assets from AssetService:GetAssetIdsForPackage, then took all the accessories off the player, rebuilt the rig, inserted new limbs (building the rig each time i added a limb) and then reparented the accessories (and rebuilt the rig)…
I rebuilt the rig a lot because it seemed that the success rate was significantly higher when rebuilding the rig.
If it helps you here is a .rblx place that I used to test out my package giverMorphTest.rbxl (20.0 KB)
For me this works flawlessly in test studio, most of the time in game. I suspect that the issue is due to a degree of lag that I have, as in my game (which can get quite laggy) I seemed to die a lot more.
From all of the debugging that I did I could not either diagnose the specific flaw in my code.
(edit) On a side note:
Instance.new(self["RIG"]["BPs"][EnumBodyPartR15], nil){Anchored = false};
Using the second argument on Instance.new is highly advised against. If you want more information, visit PSA: Don’t use Instance.new() with parent argument