In a similar thread in CA, we found that the 22kHz is a result of not having a HE-AAC decoder (which should decode lossy Tidal 96kbps stream to 44.1kHz, not 22kHz.)
If anyone finds Roon only decode it to 22kHz instead of 44.1kHz, perhaps consider asking support, state your Tidal album and Roon Core platform OS. I did a search and found that Roon had fixed HE-AAC support for Tidal back in August 2015.