Source: WowAce

It appears TomTom integration is broken, since the TomTom API no longer includes AddMFWaypoint.
To fix, I performed the following changes in Rarity\Core.lua:
Replace all AddMFWaypoint with AddWaypoint
Search for line that starts with TomTom:AddWaypoint and delete the floor argument, i.e. "coord.f or nil,"
If this change could be integrated, that would be appreciated.
Cheers