Can't enable mission - all other GPS functions working

[txpatrol]

I put together a spare frame over the weekend using a Witespy Mega EZ 3.0 Black board, ublox 6H, etc.

On my first flights on Saturday it was working flawlessly. Minimal tuning and GPS hold, RTH, baro & mag were almost perfect. I loaded several missions (keeping waypoints close and my finger on the "kill switch") and all functions were working great. I did several with multiple waypoints, bearings, RTH and land and was extremely impressed.

Then....

I was having some issues with a LED ring and bluetooth so I did some tweaking to my sketch. Stupid me for not saving the previous sketch I had been using, but on Sunday I simply could not get mission to work again. All of the other GPS and hold functions are still working well.

I've assigned aux 4 to a switch on my TX and assigned mission to mid and high on Aux. 4. I can verify that Aux 4 is switching via the GUI however it does not enable mission when the switch is thrown. Armed, unarmed, it doesn't matter.

I have verified that I have a strong GPS lock - usually 8 to 10 satellites and everything else seems to be setup and working properly.

It's driving me nuts because I know it has to be something stupid, but I just can't figure out what could have changed from what I was doing on the first day to now. It's even worse because of how well it was working on the first day I used it.

Any ideas/pointers/general tips on how I can troubleshoot this?

[FrankenberryPi]

Hey, I saw on another thread that you got your missions working again, but I've got a simpler question: how did you get your compass working in the first place? I've tried fiddling with the config and def files more than I probably should and my magnetometer always reads flat-line. Any pointers would be greatly appreciated.