If you have separate accounts for the two systems, they EACH need to be designated as "mobile accounts" and each one needs to be authorized for DNS service. There is a form to file for each vehicle. Are you getting the 390-series of channels on the system in the 5W? The one that worked last year?
If you have one account and two receivers, you may have DNS on one and not the other, or you may have lost DNS when you added the second receiver and another vehicle. There is nothing automatic about DNS - the FCC has very rigid rules that Direct must comply with. They will err on the side of caution rather than risk trouble with the FCC!
Since you get nothing when the tv is set to "Air" as the source, it may mean the antenna isn't wired to the tv. Maybe never hooked up, or maybe it was wired to the satellite receiver instead? That is an option on some receivers. What model receiver is in the motorhome?