Characters can become stuck and unable to move as they slide against very steep capsule collision. This seems to be caused as a result of ProcessLanded begin called within UCharacterMovementComponent::PhysFalling at
Using a template project, place a large capsule collision rotated slightly to have a steep incline. Place the character above the capsule collision and begin play.
Expected: The character will slide down against the capsule until reaching a walkable floor.
Result: The character stops falling and is no longer able to change location.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-77267 in the post.