I bought this card from Amazon, works a treat.
Will do! For what it is worth, I bought this Inateck card and this TOTOVIN card. The USB controller chip on both has had native Apple support since Sierra, so we should be good on the OOTB support.
I bought this Inateck card and this TOTOVIN card. The TOTOVIN card fixed my problems with the Scarlett for both audio dropouts and the Focusrite controller not working. HOWEVER, about a month after I posted that comment, the TOTOVIN card died. It's probably just a bad card that I happened to get and may not be representative. With the Inateck card, both worked as well.