Hi there, I thought I would add my voice to this as there does not seem to be any definitive answers coming from Line 6.
I have a FX100 pedal board and regularly check to see that I have the latest software (does not seem to have been many updates in the last 6 months)
I use an iPhone 6 or an older ipad and experience the same problems with dropout of the control side or editor. I have done pretty much all the things suggested in the post before without success. When I run the app, and no other app, I get the connection and can select and edit tones at will, however as soon as I start to play music through the app at the same time the connection to the FX100 is dropped and I can no longer edit. I have to turn off and reconnect to the Bluetooth and start again to get the editor working. Line6 please help.