Help w/BPCW Map 7 v3 (What's Yours Is Mine) Section 3

Had 2 fights using CapIW (sig200)with Science & Cosmic team.
Started the fight with 3,4 sometimes 5 parries then randomly he flips it on me and KO?
I had 3/4 weakness debuffs on him each time and he still flipped the stun?
Can anyone explain what I'm doing wrong and give me other options that work?
I will go in fighting it as a stun immune fight, but I was told I could parry without reservation.
Thanks!
Started the fight with 3,4 sometimes 5 parries then randomly he flips it on me and KO?
I had 3/4 weakness debuffs on him each time and he still flipped the stun?
Can anyone explain what I'm doing wrong and give me other options that work?
I will go in fighting it as a stun immune fight, but I was told I could parry without reservation.
Thanks!
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