USB-C headphone issue

So got my new iPad Pro. Not a fan of the no headphone jack. So ordered the apple USB-C to 3.5 adaptor. Plugged it in and surprise, no sound. So verified, this is supported. Took it into apple. Swapped the adaptor. Still doesn’t work. Swapped the iPad, still nothing. Tried iPhone of there showroom units,... Nope! Am I the only one with this problem? Support says it’s an IOS bug. Looking for a fix