I don't know what is going on, but my gunshmith materials and event candies went missing. If I want to be detailed, my gunshmith materials disappeared yesterday from the stack of 998, after I dismantled some weapons that gave me more gunshmith materials, and I checked, there is NO more stacks of that particular item, just the new ones I acquired. This happened to my candies too, probably the items not stacking anymore and my items went down in the toilet(and I remember NOT spending them at either Eva Levante or Banshee). I can cope with my losses, but what if someone cannot? This is why I am leaving here this forum post, maybe this error/bug will be resolved soon!
Did you check for them in your vault in game?