UHS-1 not supported as the card will not work? I use a UHS-1 card and it works fine, tried a UHS-3 32Gb too but that one failed.
Your card must be a hybrid card working via the slow bus. Nothing strange about that. Some cards don't even get the correct labels/logos, which is very bad.
Hybrid cards do work, but UHS I (Class-1/3) native cards without the compatibility logo won't. There are also UHS I Class-3 hybrid cards and there are even huge (seen up to 128 GB) SDHC only cards (typically brand-less).
Never saw an ultra fast UHS II hybrid card, which does not make too much sense anyway. UHS II cards have a dual bus and have a dual row of pins (easy for identification) and are almost as fast as SSD.