As you can see, at 7 seconds and at 25 seconds, I'm "hit" even though on my screen I've successfully interrupted the Bulbin's attack animation.
This was in co-op, where I was not the host, so I realize this could be latency, however, I'm on a good connection. And personally I feel like something like this should be client-side. That felt incredibly bad to be ghost-hit twice in a row (the third and final hit was just bad from me, but I was pretty tilted after those last hits). I've actually had this happen with non-nightmare Bulbins as well, but I don't have a clip of that, and it's much MUCH rarer. There's just some issue with interrupting the roll attack, especially with bow. It's just especially bad with the attack animation speed buff from the Nightmare anomaly.
Join a co-op game (estimated latency ~30-50ms)
(Optional) Use Bow or maybe Strikers
Get a stage with Bulbins and the Night anomaly to have Nightmare rots
Try to survive by hitting them before their roll attack can hit you
Get hit anyway
Cry
A developer has marked this issue as fixed. This means that the issue has been addressed in the current development build and will likely be in the next update.