This thing is becoming more and more frustrating since the Falcon introduction with Apex.
It would be nice to use an UAV without the thrilling of not being capable of moving it where needed.

I had same problems with Greyhawk/Ababil.
Before last release it was rarely happening, actually in the last 2 times I had an UAV I was not able to make it land or move on assigned waypoint.

Regarding the altitude setting, the possibility to manually set the value can be the best and more versatile solution.