Normcore portafilter + tamper channeling badly.

Using 18g with grinder a few clicks above lowest setting. Here are all the items I am using:

Tamper:

https://www.amazon.com/dp/B0DSLYKM31

Portafilter:

https://www.amazon.com/dp/B0F287JMGK

and the grinder:

https://www.amazon.com/dp/B0BW272XCV

I notice the tamper isn't snug and I have to press it multiple times/move it slightly each time. I see a lot of people recommend these items, so curious if I just have a defective one.