Hello there. I have a new wahoo kickr core with a brand new cassette. now i have the Problem, that in higher gears (smaller cogs) i hear a grinding noise. like for gears 1-4 its good but after that it begins. I only replaced the cassette and not the chain. i wanted to try changing the cassette to the old one on the wheel but its stuck.
maybe its not even loud and im just tripping, but i have attached 2 videos, one in lower gear with in my opinion normal sound and one with the grinding noise in higher gear.
It is hard to see on the video but it looks it looks like that is 11 speed cassette. Whereas your derraileur is Tiagra which is normally 10 speed. The grinding noise in this case is probably because it is not possible to index with 10 speed shifters on an 11 speed cassette.
Lastly never use an old chain ( which wear out fast and are cheap to replace) on a new cassette ( which wear out slower and are expensive to replace)