Flipper Favs doesn't work consistently with Cisco and Pace RNG units and HD271.
We are still working on a resolution, however, to date we have not been able to get Favs operational.
All basic features work however.
A workaround is to see if your provider has a Fvas feature in the box, then use Flipper in regular mode.
A second workaround is to see if the facility can swap out the box. I know this can be challenging, however, these providers are compatible with many boxes, and should have other devices in their lineups.