An issue that can arise is if your RootPart has Collision and a ControllerPartSensor, you leave yourself open to an edgecase where if the Rootpart gets caught on a ledge it cannot figure out that it’s still on the ground. This causes a myriad of issues such as being in the wrong spot vertically and being unable to have the controllermanager move the rig anymore.
If I had to guess it’s surely because the ledge part is so close to the sensor part that the sweep cast will just ignore it.
The best workaround is usually to have 2 Parts, one doing collision and one for the sensor. That way you can avoid the ledge issue.
However, it would be ideal if this edgecase didn’t occur out of the box.