I think you can not get sensors-info because according to "technical product specification" ST1200BTS is missing integrated BMC (baseboard management controller). This is present on the "sister-board" ST1200BTL which I'm using so I see full set of information under "Health Status" (processors, memory, storage, voltage, temperature, fan, software components, power, chassis, watchdog).
I can only add my own complaint to "hardware compatibility list". If something is listed there, it should be either fully supported or sufficiently commented every limitation (i.e. not supported 2nd NIC).