I'm also having some trouble with ANT USB service.
I installed both ANT USB and radio service and the ANT+ Demo, then the demo only showed "Enable ->" and the ant logo.
Then uninstalled the services and the demo says ANT not suported, though it should be.
My phone is a Samsung Galaxy S 2, with ICS 4.0.3
USB Host seems to work as I can read a USB drive perfectly, and checked the link above but the USB Host permission file already exists.
It could be other problem also associated with the USB host API.
For the USB I'm using a cheap USB OTG cable and an ANT USB2 Stick (Decathlon Kalenji S&D Connect)