I have a 2016 Bighorn, and had coax issues...not the same as yours but I will share what I found.
OTA issues were caused by a factory error...they did not connect the antenna coax lead to the coax cable that feeds from the power switch. Access to connection is through the antenna crank area. I used a multi-meter to test power on the roof to find this issue. I was still receiving some signals without any antenna...so it took a bit to discover that I was not getting signals that I should have been getting. Tough if you don't know what you should be getting wherever you find yourself.
SAT issues were caused by a bad piece of coax within the wall in the area of the living room tv. This issue was hard to troubleshoot as I was getting some SAT but missing channels and/or satellites when connected through the trailer coax. Sometimes it was just a weak signal strength, and sometimes it was ok. Connections were good and replacing the connectors did not help. Ultimately, wiggling and pulling on the suspect cable uncovered what must have been a damaged length of coax cable within the wall. The suspect wire in the wall was accessed from behind the fireplace...cut out and replaced by fishing new wire. While doing that, I also found that the second OTA coax cable in the wall by the living room tv has a connection using a barrel connector inside the wall...strange place for a connection.
Just plain time-consuming but you'll find it.
Best...Celt