I'm getting no music (neither FM nor GM) when I start Descent 1 with the 3dfx patch (version post-alpha 2 dated 08/29/98) from here. Descent 1 itself is patched to version 1.5

Following specs:

Mainboard Intel AN430TX with Pentium 233MMX and onboard Yamaha OPL3SA and OPL4 GM as well as onboard Ati Rage IIc+DVD (driver 4.11.2517)
64MB SDRAM
Diamond Monster 3D II with FastVoodoo2 4.6 driver
Windows 98 SE with latest VXD drivers for the Yamaha chipset (version 4.06.2343) from Vogons driver library
SD-IDE adapter with 32GB SD-card (primary master)
LG GSA-H10N DVD-RW drive (secondary master)
3com 3c509b PnP ISA NIC

The Yamaha is configured as follows: Port 220, IRQ 5, DMA 1 (WSS DMA 0), GM port 330, FM port 388. There are no resource conflicts.

When I run the Descent 1 setup.exe from within Windows 98SE I'm getting digital voice and music (either FM or GM) and they test just fine. If I start the DOS version of Descent 1 (either from Windows or DOS) I'm also getting music just fine. But once I start the 3dfx version (that requires Win9x) I'm only getting digital audio effects, no music. Doesn't matter if I configure FM or GM in setup.exe. The 3dfx patch uses its own .cfg file and I've made sure the settings for midi there are 1:1 the same as from the standard descent.cfg that's created by setup.exe. General Midi and FM work without issue from within Windows 98, when I run music software or DXdiag the music tests fine.

Is there maybe a newer version of the 3dfx patch or does it need special settings to enable music?