Which parts do you have collisions enabled for? Humanoids should only have the Head, Torso and HumanoidRootPart enabled with collisions. If that’s not the case, fix that first and see what happens.
This happens quite a bit, if you rescale your character to be small it slides around like shown in the video, so I don’t believe the script is the issue.
It’s like getting stuck on something, but everything is frictionless?
You can see the highlight is clipped, but it’s no-collide so it shouldn’t matter.
In order to get rid of this bug I had to increase the density of everything to remove the sliding , the thing that had me stuck was how the Rootpart has to be heavier than the rest of the parts because of the increased amount of parts AND I had to lower the friction SUBSTANTIALLY to compensate for it’s walkspeed and to remove the “getting stuck randomly” bug! The final thing I had to do was to increase the hipheight so it’s the same as the Y position of the rootpart to remove that weird tilt.
(If you wanted to do this with a different size model or different proportions some tinkering may be required)