Same problem here. I have an HP laptop with on board RealTek HD Audio that has minimum 16bit 48khz, with no option for 16/44 and Studio One 4 only gives me 44khz option. Plus when Studio One loads I get the failed to open Microphone Array. This has been a long standing problem and I'm not upgrading to version 5 until it's addressed.
Update. Found answer in different question. Simple
Select Audio Device, then control panel, then deselect the Exclusive Mode option. After that was able to select different sample rates available on my built in Audio device.