CLSN doesn't determine whether an attack is blockable or unblockable. Check the attack state itself and make sure there isn't some kind of time=0 in there.
I used animelem = 1, I used appropriate hit/guard flags
Here is the hitstate itself.
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[State 210]
Type = HitDef
Trigger1 = animelem = 1
Id = 224
attr = S,NA
damage = 82,12
priority = 4, Hit
animType = Up
ground.Type = High
air.Type = High
hitflag = MAFD
guardflag = L
pausetime = 8,8
guard.pausetime = 8,8
sparkno = s-1
guard.sparkno = S-1
sparkxy = -2,-94
HitSound = s200,1
guardsound = s297,0
ground.slidetime = 7
ground.hittime = 11
guard.slidetime = 6
guard.hittime = 9
air.hittime = 12
ground.velocity = -1.3, -10
air.velocity = -1.3,-10
fall.recover = 0
fall = 1
fall.recovertime = 35
fall.yvelocity = -1
fall.envshake.time = 9
yaccel = .49
ground.cornerpush.veloff = -(1.5+fvar(20))*5.3*(const(size.xscale)/0.50)*ifelse(var(50),0.66,1.0)
air.cornerpush.veloff = -(1.5+fvar(20))*3.45*(const(size.xscale)/0.50)*ifelse(var(50),0.66,1.0)
guard.cornerpush.veloff = -(1.5+fvar(20))*5.0*(const(size.xscale)/0.50)*ifelse(var(50),0.66,1.0)
getpower = 15,0
givepower = 1,0
The state itself is
S - Standing
A - Attack
S - Standing Physics