Did some testing offline. The drones are resetting back to the starting end of the runway. If you are out of a certain (unknown- did not check) range they explode. If you have not gone that far they remain intact. You can even go back and collect them if you don't have enough runway to compleat take off.
I tried several models and even the ones that are not recently updated do this. You can even get the wheels off the ground a few feet, land and they do this. You can bring the wheels up, land while still over the runway and they do this.
However I did take a set of Betties around without the wheels going up and the drones were in line- low AGL and not in final formation. I was able to land them without problems. I then taxied to the other end and they remained where they stopped and intact.
I think the drones have at least 4 stages of control.
1. Match speed but are still tied to runway. This is evedent by you veering off runway but they follow the concrete. Player/FM/Field controlled (by field control I mean the FM is using info about the field)
2. AGL point that drones follow you but do not form up. Player/FM controlled
3. AGL point that drones form up. Player/FM controlled
4. AGL and wheels down where drones attempt to land . Player/FM/Field controlled.
Although this should be counted as a bug IMHO, you need to get to step #2 if you want to prevent this.
For the time being I suggest that that once large bombers start rolling they should compleat takeoff. Smaller ones can stop fast enough if the problem is realised quickly.