FYI, I've had one case where the Inspire wouldn't go into travel mode on an appropriate surface, and wouldn't even make the attempt. It was after a flight where the DJI Pilot app had crashed while in the air, and my hypothesis is that the restarted app had a landing-gear state mismatch with the aircraft. The app said it was in travel mode, but the aircraft was physically in flight mode. Toggling the landing-gear toggle 4x didn't help, and in the app it said "Exit Travel Mode" on the appropriate button. Cycling power on everything didn't help.
This was resolved by swapping the battery. I think swapping the battery forced a re-synch of the landing gear state between the aircraft and the app, which then realized the AC was in flight mode. I could then put it into travel mode, swapped in the original battery, exited travel mode, and everything was in synch again.
Wierd, but I saw it myself. Why the app didn't re-synch state with the AC when it was power cycled is strange. My only guess is that the app looks at the serial number or other identifier of the battery, and if it's the same as the previous one, it trusts it's current state and doesn't re-synch. Dunno.