This is more of an inquiry into the behavior of RopeConstraint, than it is a request for a solution. I have my workaround. I don’t understand WHY it happens, or if I am doing something wrong. Getting a handle on this could help several developers, but more on that later.
BOTH issues are network ownership related. RopeConstraint acts like it only works on clients. That’s a physics thing, but as you can see below, there are some non-physic behaviors that don’t make sense.
My setup: My character (on horseback) is pulling a physics based cart.
Issue 1: Humanoid.Running does not trigger on the server while the network ownership of the RopeConstraint is the player. I use a server side custom animate script, so this means no animation plays while the rope is client side. Workaround: set ownership of the player to the server while on horseback. This has a side effect of disabling my GUI based run/walk script, so I hate it!
Issue 2: Deleting Attachment 1 (when the cart flips over) on the RopeConstraint only deletes the attachment on the client, as if I were running a local script! This was very frustrating. Workaround: use Enabled/Disabled instead.
If this sounds like bugs, I will report them as bugs (I may do that anyway), but I don’t know much about the physics part of Roblox, so this may be my fault. This is not the first time that RopeConstraints have caused this kind of trouble, so it doesn’t feel like my doing.
Rope constraints messing with network ownership - Bug Reports / Engine Bugs - DevForum | Roblox