Weirdest stick drift issue continues after opening and cleaning

My Xbox controller has something that isn’t quite stick drift but can’t be quickly described as anything else. If I push my left stick up or down, the controller doesn’t recognize that the stick has gone back to resting position. If I click L3, the controller recognizes itself at the resting position. After I opened the housing unit, cleaned it well, replaced the stick, and put the cover back on, the issue is still happening. Has anyone else had this sort of issue? Can anyone help me?