I would guess that whenever you are jumping, it is adding the velocity from the jump onto the velocity your sprite already has from the lift, or multiplying by it, or something like that.
Without seeing your blueprints, it would be hard to tell.
I understand what you said NightHawk… But I was looking the blueprint, and I didnt find anything related to it…
This is the blueprint of the Intelligent Lift, if you can see something that can be related with it, please let me know…
Check and see if your jumpzvelocity is being changed in your blueprints. I think some of the templates have it set so that your jumpzvelocity changes with your speed.