I received a 2H mace which I can't use as a Monk

Support Bug Report
1

I was running my Delves today and I received 2H maces on my windwalker monk. But game says i don’t have the proficiency to use it? Can’t i get a refund on my bountiful key?
I received the [Machine Gob’s Iron Grin].

2

helps to mention the name of the mace