Sorry for the very basic question, but... what other ASIO apps (DAWs, soft-synths) have you tried with your card that work with those sample rates?
btw, 48K works also ok on my ASIO audio interfaces.
...and, being "professional" doesn't mean it's done right or without bugs. Usually ASIO drivers or even the WDM drivers of professional audio interfaces have issues that need to be reported to the manufacturer support to be fixed... if that's what's happening in this case.