What's going on

I don't know when this started but I don't recall this always being a thing. I've noticed that when I'm blocking the game will take me OUT of shield during some attacks. It's not a matter of me letting go of shield by any means but certain moves will literally take me out of shield while holding. I've never noticed this before and I hate it. I'm a sitting duck for combos that take me out of shield. But shouldn't shield hold until it breaks or I let go?