Although I also have the Pike Air from CRC and haven’t yet experienced what you describe, I did have a set of Revs which sound like they had a similar knocking and put it down to this from TFT site…
My U-Turn air fork knocks slightly, what is this?
There’s play in the travel adjust helix. A small amount of play is necessary because if it was tight you wouldn’t be able to turn it, however this can cause a knock. During service, we reduce this as much as possible but it can never be completely eliminated.
I’d give TFT a ring