Auto-block - bug or intended?

You can’t auto block low attacks. Auto block is only for high and mid attacks. you have to manually block low attacks. So if a overhead and low connect on the same time frame you’ll block both. It’s to prevent unblockable setups (literally speaking).

You are wrong.

You can auto-block lows

I tested it with Mira’s shadow bats and a cr.MK

I’ll have to test for myself then.

I’m not sure.

I can’t test it now, but try to block Omen’s shadow slide first hit and then just block high.

The move seems to not be a true blockstring,since you get hit by the remaining hits.

I’m speaking out of my memory, but this happens at least in shadow lords

“Block Stop
The duration in which you are unable to switch your guard while blocking an attack. This is also usually the window of time that you are able to input a tech hit or guard cancel (in Vampire Savior), and is a time prior to entering blockstun where your character is frozen in place and not being knocked back.”

You might be right. That would explain many things.

EDIT:
Yes I think you are 100% right. You can’t change your block stance during those moves. That’s why the game is doing it for you. Thank you @DEClimax