Hello escapees, trying to fit an 11 speed Shimano groupset to a 2018 Kona Rove having done absolutely zero background research if this is possible. Having serious issues getting the brakes mounted. The bike came with a pair of Hayes CX cable disc brakes which I believe are IS mount (???). Tried a IS to flat mount adapter but that was no bueno. Anyone know what the solution may be? A set of IS mount hydraulic calipers? This is a winter bike so there is no solution too cheap/crap.
Some pictures of your situation would help helping you. From the product photo it looks like there are indeed IS brake mounts with Post mount adapters for post mount calipers.
IS to Flat mount adapters do exist, so you either mounted it wrong, the adapter has wrong dimensions or it won’t fit the frame. 
Alternatively you could swap the FM calipers with PM calipers from the mtb line and use the existing IS/PM adapter.
Appreciate the response! Had a double check of the IS to FM and turns out it’s just the rear that doesn’t fit - the curve of the adapter interferes with the mounts unfortunately. Guess it’s time to mix and match calipers.