Sorry for extra long time to reply here, just in case anyone else ends up here. For the foreseeable future, ANT on multi-mode comm chips will not support continuous scan mode, due to co-existence issues with the other wireless protocols on the device, power usage concerns, and other limitations.
For mobile devices that support it, the solution is to use an external adapter such as an ANT USBm stick over USB OTG. However, the current library does not have that feature available yet, and currently the legacy library can only access the usb adapter when it is on a phone without built-in ANT support. So the solutions are not great right now.
We will be addressing solutions for continuous scanning, and long term background scanning in future releases.