both chaos and sleep fall in same CC category what cannot be overlapped so when you get opponent is under chaos and that unit just happens to be target who izuna puts sleep so it overlaps that chaos changes to sleep debuff instead. (both chaos and sleep affect movement of unit making them ether miss turn or attack their own teammate so those 2 cannot coexist on same target)

(info here might not be 100% accurate)

blindness and immobile are is same category as well making them do similar thing but there is difference in actual effect as blindness is makes unit "blind" so it cannot see where attack or movement goes while other hand immobile stops all type of movement what unit can have. (as in blind person can move but it cannot see what he does and person who is immobilized person cannot do any type of movement. (So in game they both affect same thing but same time they are different so they can coexist) Sleep and chaos other hand are both affect in some way of Psychological dmg (forcing person to sleep or making them confused so they see teammates as enemy)

(still not guaranteed that info is 100% correct)

np :P ye too many variables and as retired player, so didnt remember how immobile and sleep stack went but as in old days used sleep, chaos cancer teams (1.0 -3.0 meta for me. ) so that part stayed in some what in my mind :)