Poly is out of the drawer and back in play, and I suspect it may be back for the long run.
There was a post about this in the first 100 pages--maybe the first 50--but it took me six months to try it.
Teaming the Poly/Mojo with a WD My Passport Wireless Pro has solved every problem I ever had. GoFigure was able to see and connect to the WD's Wi-Fi network. AirPlay is bypassed, so every PCM resolution from 44.1/16 to 192/24, plus DSD 64, all play natively. Glider can find every track, regardless of whether it's on the iPhone 8, Poly's SD card, or the WD drive.
So far, no hiccups of any kind. Warning: if you store your music library on a Mac system, you may need to invest $20 in a copy of Paragon NTFS software in order to drag and drop files to the WD drive (the WD manual says it's included on the drive, but it wasn't on mine). The 3Tb drive can now be had for as little as USD 109.95 (Fry's).
I was ready to give up on Mojo/Poly a month ago, and invest the sale proceeds in a DAP. Now I'm glad I didn't.