Firstly please post a screenshot of your macro so we can double check the configuration looks correct.
Assuming it is correct, could you create a test macro as follows:
Trigger -> Mobile Service Available
Action -> User log "mobile service available"
It will be interesting to know if you ever see this firing as it uses the same global broadcast listener as the constraint uses to determine if a signal is available or not. If this macro does fire when expected it would indicate that something is failing when initializing the constraint (which means I have something to fix!)