The only other things that comes to mind, are some issues that I too have had. On occasion I noticed that my video signal will be frozen on an image from an earlier time. And sometimes just black, with maybe intermittent blinking. Later I realized that either I accidentally pressed the auto capture (3second intervals) button, or it switched to that mode on its own. It's happened several times to me. I realized that many of the times when I was having a problem with the phone connection it was in that mode, and overwhelming the little memory card. Photos every few seconds, while its trying to write them to the memory just didn't work while trying to live stream. Later I adjusted the photo preview from high quality to low quality and though what I see on screen isn't great quality, it's good enough for me to line up my shots, and the connection works well. It still slips into that mode sometimes, but I can usually recycle the app to allow me to get back into the setting and change it to single photo.
I know it's not exactly the problem you've described, but the fix, whatever it may be, might just have to do with reducing the demands on the connection, one by one. I would take the blades off, and try and get the camera nice and set up while in you home nice and comfortably, just to see if you can, without being out in the wind or elements. Then play with the camera setting without flying, just to get the feel( since it sounds like you haven't been able to do with all of the issues stated). Hopefully it's just one of those things where it's doing to much, like pressing enter on a pc, while its updating programs in the background. Also be sure to close all other apps on you smart device if you didn't already.
Good luck fellas, I hope there is something useful in all that babble. I'm truly enjoying my flights, and I'm sure you will too.
Rich