Which APM board are you using?
Have you re-set the APM to factory spec using the CLI, then tried using the latest mission planner to load the code into the APM?
Hello ken, That reset normally cures 9 out of 10 issues, appears we might be on number 10 :(
Can you show a screen shot of where the planner is getting stuck?
Can you try this code with the IDE and see what happens:
Please disconnect all motors / lipo before uploading this code, this is not a copter code, I just want to see if the 1280 board is accepting a code known to work on it!
The screen shot was from IDE not mission planner I saw?
There are a few items which need to be set....
Might be easier to help you if you get team viewer, I can take a look at your screen with you. I use it to support my customers with Tech advice all the time, it's great and did I say free :)
Email me at firstname.lastname@example.org if you want to go down that road, I can book a slot with you :)