Following the setup in the tutorials I’ve linked does not provide the results that you’re experiencing. After looking into your project, the workflow that you are using to set up your elevator is not recommended, which is why I provided the tutorial links for you to look at.
The reason that you cannot jump when the lift is moving is because it is causing the character to be slightly off the ground based on how you are moving the platform, which means that it does not think that it is possible to jump at that time.
I’ve seen the videos, but when I was in your project I did not experience the character becoming stuck in the lift.
Please take a look at the tutorials I’ve provided and see if copying those setups provides you with the same results, and then we can begin to determine if there is a potential issue. In my setup that I created in a clean project, I was able to get the elevator working properly in a few ways. You can create a Matinee that has a movement track that moves the elevator. You can also use a timeline for this purpose as well, which would allow the elevator to have much smoother and more consistent movement.
The ways that you have set up your lift all seem to be using the Set Actor Location node, which I don’t recommend because it can cause collision issues when used in combination with the capsule on the Third Person Character.
While I do recognize and understand the issues that you are experiencing, I’m suggesting that you create your lift in a different manner that is more efficient, as this should eliminate the problems that you are having when it comes to your character being unable to jump and getting stuck in the lift.
Let me know if you have any further questions.