We have a 98 Signature 42 ft. with a Cummins 10 l.

[RamiDav]

Check your transfer switch
Monaco used a trans sw named IOTA , it was recalled as a fire hazard .
Now Monaco and IOTA have bankrupted so you can't call them you
will have to pay for it yourself .

Ray

[vito.a]

Steve, your issue is definitely the Heart Trace Freedom inverter not providing pass through to the second AC circuit breaker panel.
When you are ready for a permanent fix:
Verify the two 30a breakers in your main electrical panel are providing power to the inverter.
Then you need to locate the inverter and check for a push in circuit breaker.
Check the inverter input voltage with a meter.
Next I would perform a reset on the inverter.
Hope this helps.
Good luck.