Low Fire Charge Not Applying to Attacks

Description of the bug: (optional screenshot/video): Fire charge's additional damage multipler no longer applies to my weapon attacks.
What is supposed to happen?: As per skill description, I am supposed to deal 163% more damage.
Where did you find and/or notice this bug?: I have noticed this bug initially at MPQ after levelling up and applying SP to fire charge, raising it from 15 to 18. Further testing shows this bug happens to all maps.
A step-by-step guide to re-producing this bug (optional):
Extra information (optional):

• Short youtube video showing the multiplier not being applied to a fire neutral mob. Character is using power strike.
• Fire weak mobs still get a ~50% damage multiplier.
• It does appear that some damage multiplier on all mobs is being added, but not 163% - closer to 110%.
• Have not levelled up the skill further to see if this only applies to lvl 18 fire charge.
• Restarting the client does not fix the issue.
  
• Have not tested on multiple PC's.