Player slips off moving platform if Animator Component enabled

Hello,

I want to make a futuristic flying train in which the player can move.

To make the player move with the same speed as the train I have set the player as a child of the train.

I have replaced the third Person Controller-animations from the Standard Assets with custom animations from mixamo.

If I deactivate the Animator or ThirdPersonCharacter-script on the player and adding a box collider for more contact points, it will prevent the player from slipping, but the script and the Animator has to be on, to move the player properly.

However, if I turn the Animator and tpc-script on, the players' acceleration will differ from the trains' and it slips off the train again.

It seems that this issue has to do with the animation properties, but I can not get it to work. Is there any way to fix this?

Any help is appreciated!