I might have a partial solution now. Simply commenting out the following two lines helped:
if (libusb_reset_device(dev_handle)!=0)
return ReportError(-1, "USB reset failed", libusb_strerror(libusb_error(r)));
I recompiled the library and was able to successfully record an I/Q stream.
As this is just a quick-and-dirty hack (and I’m not sure if there are any bad side effects), I’d still like to see the problem solved more cleanly.