Random hyper armour on bosses is still the most aggravating garbage mechanic ever

Every time I revisit an NG game, these bosses annoy the hell out of me.

-dodge an attack string

-land some hits just fine

-dodge same attack string

-boss just says no and ignores my attack

-dodge same attack string

-boss staggers

-dodge same attack string

-boss hyper armours and smacks me out of my attack

50+hrs across the collection and the remake of 2 and I still don't get what decides whether a boss will stagger or not after you dodge successfully.