Thumbstick not registering certain Movement

I have a scuf Vantage that I have been having stick drift issues. I replaced the thumbsticks and when I went to test everything to see if it was now working fine I noticed on both sticks when I press left and up all is fine, but when I press right and down, it’ll start going in that direction but then quickly switch to the opposite direction.

Are the new sticks I got faulty or could it be another issue causing it?