Do you mean that 1 of your 2 Magnums is Float Charging while simultaneously also Inverting? Or did you mean to say that 1 Magnum is Inverting and the other Magnum is Float Charging? If you meant the latter situation first check the breaker in the main panel for the Magnum that is inverting. Most likely cause is there is no AC at the input of one Magnum so if AC input breakers are OK check for a tripped breaker on the Magnum itself.
2021 Entegra Aspire 44W
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2013 Tiffin Allegro Open Road