Typically, the Inverter in an RV is wired directly to the COACH battery(s) and not through the 12-VDC Fuse panel. This is because Inverters built into an Rv by the manufacturer are usually built with their own internal fuse for protection. You should check the Inverter for a fuse holder mounted on the end of the unit.
A quick look at similar Xantrax Inverters does not show a fuse holder but they do have a fan which should always be running if it is operating, and it has a digital display which should indicate the voltage. If neither of these are operating then your Inverter is most likely bad. especially if you use a multimeter and measure the presence of 12-VDC on the input terminals of the Inverter.