GM Map interferes with inserts - Please help


I’ve been struggling with this issue for a while now.

I use a GM Drum map through “Microsoft GS Wavetable Synth” (only option available). The GM Map works fine in the editor, however, when applying an Insert (specifically RoomWorks Reverb) the reverb doesn’t apply at all.

I then turn off the GM Map and the insert is now applied. This isn’t a crucial issue but it is annoying having to switch the GM Map off to hear the inserts applied.

Does anybody know why this would happen?