Uhh, did you buy a counterfeit? Cause that's typical behaviour for em, spoofed capacity when it only has 16gb of memory.
I'd go with something in a B tier brand, cause they're not plagued with knockoffs... So Kingston or Adata or what have you. And get something that you can actually find reviews of that mention the actual read/write speeds, cause who gives a shit if it's reliable when it only writes at 10mb/s.