I’ve got a brand new x01 cassette and chain with a gx mech. It’s fine in all gears after setup including the 50t. But the next one down, the 42t only, is a bit grumbly. I think it’s trying to fall off the top, so I’m thinking it’s just sticky new chain and will bed in. Any thoughts? If it was chain line it would be a problem on the 50t, I’d have thought. Or super bad if the mech/hanger was bent (all new as well).

Had this on my new GX after a couple of rides. Retensioning the cable sorted it.

That’s deffo worth a go. Ta.