Track down the Six Pack of Solenoids, and tap the ones that feed your Tavel Mode air feed. And it would not hurt to spray some soapy water on the connections involve for leaks. All that being said, sometimes the HWH brains go out on you. Leveling can work, but the circuits for Travel Mode can go out. HWH was pretty backed up last time I checked, but calling and asking for a Tech to call you back will get you on the list. They can walk you thru some diagnostics to determine if the HWH brain needs surgery
And while not ideal, the manual travel mode does keep you going. We did several thousand miles in our 04 Allure that way in I think 2017 (6 Pack issue on ours.). And this year our 07 Magna got the front leveler arm 'jammed' in the slot (That when I looked i did not notice, so we were not going into proper ride height for travel.). We did the manual raise eyeballing ride height (A Fist with the other hand Flat on top of it, from the top of the tire to the arch of the wheel well, on the Magna
!)... It's not a fuse on the 07 era Magna, you unplug a harness from the control box in the front basement (The one with all red wires going into it. On our coach, it was the second from the left while looking in at the box, top side of the box.).
Good luck, and please share what you find out - as it could help others in the future