You sure about this one? I’m not 100% certain about Icecar by itself, but one of my buddies used to like to throw swords and follow them with Icecar, which resulted in several occasions where I Drive-countered the projectile, and Jin wound up close enough to get grabbed by the ensuing counter. He learned to stop doing that pretty quickly.
I’ll have to check Icecar myself at some point.
If you’re actually getting hit by the move, then that honestly sounds more like you’re just missing the timing completely. Haku’s Drive, so far as I know, should counter anything that can cause hit-stun, which is essentially anything that causes damage and isn’t a grab. Even if it doesn’t actually throw the opponent, it should still nullify the hit you counter and leave Haku invulnerable for a bit.
Those 2 moves (214D and 6D) are actually very, very slow compared to the rest of Ragna’s moveset, so I wouldn’t be at all surprised if you’re just doing your counter too early.
If you’re using 5D, btw, remember that it actually has some start-up, while 2D, 6D and j.D are active much earlier (1-frame startup, I think). 5D has more active frames though. Between the start-up on 5D and the small active windows on the others, the timing for effective counters is actually fairly tight.
And I’m no expert, but the only thing I’ve seen (so far, at least) that affects whether Haku actually counter-attacks successfully is distance. Something touches the disk, Haku puts his hand out, and if he can reach his opponent they get thrown into the ground. Countering a move that has invulnerability frames might get a little wonky, but I’m not sure how many moves in BB have invulnerability that outlasts their start-up by a significant margin. (Jin’s 623 C, Inferno Divider? Again, must test these myself.) In theory though, you could successfully nullify the hit, and then have Haku’s counter attack miss the opponent because they’re still invulnerable.