I had a similar issue on a 2017 Thor Four Winds. After replacing the 5 amp fuse, which was behind my fuse/power panel. The switch would work but the battery disconnect would still not turn disconnect. In my case, the battery disconnect shorted out in the on position.
I also had the battery disconnect switch without the two built on 5 amp fuses. I ended up using the battery disconnect switch with the two 5 amp fuses but left out the fuses since the provided no value for my application (panel monitors); make sure you use the original 5 amp pigtail. I also added a 100 amp DC circuit breaker to protect the battery disconnect from future surges. You may require a higher amp depending on your system.
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