I was trying to use my Mavic Air in the woods today.  I was in a clearing with about 20 feet at it's narrowest and completely open above.  I could only get it to go up about 15 feet before it would stop.

• It was not a restricted area
• The flight restriction data was not up to date but I had flown the day before with no issue somewhere else
• The GPS was never more than 7 satelites but that shouldn't have prevented flight
• I tried enabling and disabling the colision avoidence on the left button
• And I tried enabling and disabling sport mode
  

I was reviewing the flight history and it said I was too close to an airport (which I wasn't) and then got the message "Maximum Flight Altitude Reached. Adjust MC setting if required".  I'm guessing the max altitude was because it thought I was near an airport since it was at 5m at the time and I have the max altitude set to 122m.
It seems the drone was confused as to where I was.  (My phone GPS was working fine) I did a search and saw that people suggest opening the App where you have a good signal and keep it open until you are done flying.  I'm not sure how that would help given my phone always knew where I was.
After getting home I flew it from my back yard where there is no GPS and has no issue.  I did update the flight restriction information before flying it at home thoogh.