Hi yuun, I’m not the series creator, but he has addressed this in the Part 11 video. Can you have a look and see if it solves your problem? I’ve tagged the time in the video where he explains the bugfixes / improvements.
Glad you figured it out. Sorry I wasn’t able to pinpoint the issue for you.
If it helps, kinematic objects are objects that are able to collide and change the trajectories (i.e. velocities0 of other Rigidbodies, but are not able to have their velocities affected by other objects themselves. They are used in instances where you need moving objects to affect the physics of other free-moving Rigidbodies, but you also don’t want these moving objects to be affected by physics themselves, such as:
Moving platforms in platformers: If these moving platforms move off course, it may break your level!
Player or AI-controlled characters: You will need them to have Rigidbodies if you want them to be able to collide with and knock other physics objects around, but you don’t want them to be affected by physics themselves, since your own scripts will be controlling their movement.