Oddly, I had the same issue with one of My H's last fall. DO NOT FLY with this condition until it's sorted out. When experiencing this issue -- exactly as described where the gear only move a little -- I had a bad fly-away - complete loss of control when I toggled between Rabbit and Turtle mode. It went a mile and crashed. Something is NOT right - and I'd suggest to not fly it until it's sorted out. Call Yuneec for help (oddly too -- I had Yuneec on the phone when experiencing this problem getting help and while trying different things -- I had to throw the phone down and try to rescue. When the H disappeared in the horizon, I picked up my phone -- and Yuneec was still there! I reported what happened.
Unfortunately, the H was destroyed. The logs showed issues with Compass / GPS. So, perhaps if you have this issue -- it can't determine it's altitude and becomes confused? Who knows.
One thing I would do is a complete re-set of the controller and H. Remove the ST16 battery, clear app data, Re-calibrate everything from scratch. After calibration (indoors on a level surface), bring outside without Props and power up - calibrate the compass and let it sit for 15 mins. MAKE SURE the compass calibration is successful with the restart sounds. Just because the arm lights go back to normal in calibration doesn't mean that calibration was successful. You need to hear the start up sound.
I'm no expert here - just a lot of experience with the H's - best advice -- Call Yuneec.