Hey ,
I spoke with developers about this issue, and it sounds like they’ve been working on improving platform movement in relation to characters using CharacterMovement component. There have already been some improvements which should make it into 4.3, but a more robust system should be coming soon as well.
In meantime, check out solution posted here:
You can also consider using a different method to move your platform. Instead of using a Matinee, you can use a Timeline curve to set position of platform. This may introduce other issues if you’re moving platform in any other way than up and down, but shouldn’t have issue of falling while jumping. Again, this system is being improved upon as well.
Hope that helps!