Help! Why my shifter is stuck at the top??

Its really hard to shift up, and when i do it get stuck at the top and i have to push it down. Second gear is the hardest but the problem is there till 6th. Downshifting works fine. I tighten the liver to the fear rode but it didn't solve the issue.This problem was there slightly for sometimes on and off, and when i mentioned this at the 4th service,ktm service centre kind of shrugged it off. What might the issue?? Bike: Ktm 390 adventure, odo: 19k. 2023 model.