So you are using firmware 1.7.40 on the remote controller? My friend had the same issue where landing gear would not go in travel mode using either the app or the switch on the RC. After updating the RC it all worked.
Do you have the VPS enabled? Are you trying to do this on a smooth flat surface? Can you connect to the DJI Go app, get camera view, and confrim what firmware versions you have on your unit?
This is just a quick thank you to those who shared the same issue and those who offered solutions. I had the same problem on a one week old Inspire 1 v2.0. My issue turned out to be the surface I was on. Seems Inspire likes dark and smooth surfaces. No grass or carpet.
Enal Posted at 2016-12-2 06:44
Suddenly after a flight today mine won't enter travel mode. I thought my case suddenly grew bigger! ...
You may need to check the VPS sensors to see if they need to be cleaned. In addition, what kind of surface would you attempting to switch to travel mode on? An IMU calibration can help with the altitude reading as well.
I figured out my problem... It's the hard surface issue!
Meaning that I was holding the Inspire in my hand about 3ft off the ground when I put it into Travel Mode instead of sitting it on the top of the case or hard flat surface.
Last night I put a battery in it and put it into Fly Mode and back into Travel Mode and it was fine...