Why has a debuff with a 100% chance of being inflicted not been inflicted on a target?

The chance a debuff will be inflicted is dependent on the effects of both the target and the inflictor’s stats, which will determine the success rate for inflicting that debuff.
Due to this, even if a debuff has a 100% chance of being inflicted, the infliction of that debuff will not always be successful.

Success rates for inflicting a debuff are calculated via the following:

• If a debuff’s chance of being inflicted is 30%, the success rate for the debuff being inflicted will be:
  30% × (the likelihood of success calculated based on the Debuff ACC stat of the inflictor and the Debuff RES stat of the target, as well as any increases or decreases that were applied to those stats via buffs or debuffs)
• If a debuff’s chance of being inflicted is 100%, the success rate for the debuff being inflicted will be:
  100% × (the likelihood of success calculated based on the Debuff ACC stat of the inflictor and the Debuff RES stat of the target, as well as any increases or decreases that were applied to those stats via buffs or debuffs)

*Skills that do not state their chance of being inflicted will be calculated the same as the example for a success rate of 100%.
*Dispelling a buff is not the same as inflicting a debuff, but the success rate for dispelling a buff is calculated via the same methods mentioned above.