Two things are happening.
One: you need to NOT apply any rotation to the character capsule unless the trace detects a flagged surface; unless you’re designing a Super Mario Galaxy style thing where moving across non-flat surfaces is something you always do, you want to avoid problems by not performing the wall cling calculation unless the surface calls for it.
Two: You need to make sure that the player is always in the FLYING mode when he should be walking on walls, and then set up his AnimBP accordingly. See, what’s happening is that the player is moving past the “walkable surface” angle and the system tries to make him FALL; he enters the falling state, gravity takes over and starts adding a downward force, etc.
The flying state makes the player check for collisions in all directions and never applies gravity or enters the “fall” state which causes an anim transition. If the player is in the flying state, you can use exclusively the Add Force movement without him launched off the ramp by the attempt to enter a falling state.
Hang on, I’ll try to implement it in my game and see if I can make it work.