with wmudmount-2.0 and using the AfterStep 2.2.12 Wharf command:
*MonitorWharf mounter - Swallow "wmudmount" wmudmount -n none --exclude-system-volumes &
I get a solid, white 64x64 square in the MonitorWharf, and the actual applet resides on the opposite side, in the upper left corner of my desktop at x=-5 (about 5 pixels are off-screen), y=5 (approx 5 pixels down from the top). The applet in the upper left actually seems fully functional (arrows index, nice new icons display).
The prior version (1.13) worked well.