Make sure you have the stick back at neutral then. Quarter circle motion should never get you command grab unless you’re pressing and extra direction during the jump.
I’m not 100% sure on seth because I remember stuff like cl.hp xx mk rollkicks doesn’t make you automatically crossup, but if you are crossing up, doing the motion non crossup works.
I do it all the time vs shotos for the crossup divekick. Maybe test the setup vs then first and see if the os comes out? Could be an issue with seth’s height…dunno.
Don’t have access to the game for a few days unfortunately