Just experienced an unpleasant situation that I like to share.
After a flight in foggy conditions I could not land.  Ascent, left, right, everything worked except descending.  Pushing the stick down did nothing.  Only after an RTH, which also did not run normally, I could regain control and land.  Could moisture have been the cause?  The legs under the propellers were fairly wet.

Did you try turning obstacle avoidance off?  I know when I have flown into mist or fog it would cause the sensor to show it as an obstacle.  I had to turn them off to fly uninterrupted through it....

I didn't thought about that.  I tried sport mode, I thought I would regain full control again.  No luck.
RTH did show ‘Obstacle Avoided. Revise Flight Route’, so that must have been the cause.  Thanks for the tip.

Hello and good day TrippleDelta. Thank you for reaching out and for the inquiry. It is not recommended to fly the aircraft on foggy environment. When flying on foggy environment, the vision system of the said drone  might be affected, if the vision system is affected an accident might happen. Thank you for your understanding and support. I will be posting a list on how to utilize the vision system of your drone properly. Thank you.