Maybe Texas is using a different isolator now. Maybe all SMB factories use a different isolator now.
My van was built in Indiana in 2004 and has a SurePower isolator.
If you open the printable brochure, you will see this product will charge the starting batteries from the solar (or shore) power after the house batteries are charged to 13.2V. Obviously, it charges the house batteries from the van electrical system, but only after the starting batteries are charged up to 13.2V.
And mine works exactly that way.