[JRTJH]

Looking at the floorplan and a couple of pictures of a 2018 Hideout 28RKS online, your refrigerator sits on the back wall with the water heater directly under it. The water lines run from there, along the back wall inside the cupboard to the curb side, make a 90 degree turn and run along the curbside wall, under the outdoor kitchen (range and refrigerator) and make another 90 degree turn to go to the kitchen sink.

There is no insulation under the refrigerator floor, there is an uninsulated "outdoor shower" with hot and cold water lines and only a 1" Styrofoam insulated door to protect the outdoor kitchen. All of those areas are subject to freezing, especially if you didn't leave the cupboard doors open to get some heat into them. Warming the water lines (next to the furnace) where they make that 90 degree turn to the sink will not protect them from freezing under the outdoor kitchen, or at the connections to the outdoor shower or under the refrigerator, behind the water heater.

Since you have no hot water in the bathroom or the kitchen, I'd suspect that it's frozen behind the water heater where it "Tee's" to go in both directions. The cold water line, who knows, since it's operable in the bathroom but not the kitchen, it could be anywhere along the run.