I recently discovered xanthan gum and bought a jar to try this amazing thickener for myself. When opening the jar I however noticed a slightly "corked" smell to the powder itself. I made a thick (~5g/1L) mixture with water to see if the taste was noticable, which it was. It was also noticeable in a thinner sweet cherry dessert sauce.
All sources online refer to xanthan gum as being completely tasteless - did I just get a bad batch? For reference, the brand and specific product is Sosa Pure xantham gum.
OK to sum up what this is. This can be a multitude of things separate or combined. Since its a cork smell, i would say throw that batch out and get a new one and try it. If its the same thing, then report it on their website (If they have one) and just get a different brand. it might be molding, or staling of the gum. Either that or they make Juicy fruit gum out of the game stuff and its just not reliable. ANYWAYS, i would say get a different brand nonetheless and try that.