It does whenever a character does a move where they recover off axis(Omega 22/88B, Nightmare 22/88B, Sieg 22/88B) because Sieg's 22/88B hits slightly off axis and if the character he is trying to hit is off axis it has a chance to whiff right beside them since the move has a really narrow...
The primary issue with 22/88 B is that it's one of the more inconsistent moves Siegfried has. He has a few combos were doing 22 or 88 will make you whiff whereas the opposite input will hit. It's odd.
I agree pretty much with what Slayer says. Learning agA and using better pokes such as B6, 1K, 3K, etc. will take you a long way. Other huge thing to learn to get better with Sieg is to learn to keep the opponent at the tip range of your weapon the best you can. If you can do that you'll be able...
That's because if you're on 1P side 22BB(88BB on 2P side) whiffs after hitting with SRSH B. You need to do 88BB. It's the opposite for SBH B. After hitting with SBH B you want to do 22BB but not 88BB.