HEOS / Tidal / Marantz / Multi-channel

My home theater is based on a Marantz 11.2-ch AVR. It decodes 5.1 content reliably in most cases. But when accessing Tidal multichannel content through its built-in HEOS function -- managed by the HEOS Android app -- content arrives at the AVR's inputs as a stereo mixdown.

Has anyone been able to stream 5.1 or higher multichannel content from Tidal via HEOS -- with a Marantz or other brand of multichannel receiver? Before I continue to hit my head against the wall, I’m starting to wonder if this is an insurmountable HEOS constraint.