Adafruit Feather M0 only connects in bootloader mode

Hi, I’m using a pair of Adafruit Feather M0 RFM69 Packet Radio boards and for whatever reason sketch uploads always fail unless the board is in bootloader mode. The failure message is “Device not found on ttyACM0”
(or something pretty close to that!). It isn’t really a problem as long as I remember to double click the reset switch, but as it isn’t exactly how it’s supposed to go, has anyone any suggestions? The operating system is Fedora 27 and the Arduino IDE version is 1.8.5-linux64.

I’m afraid you have me at a loss with the M0 boards, I haven’t tried them yet!

Have you stepped through the setup instructions here? Specifically with respect to the udev rules:

Yeah. Turns out the correct group for fedora users is ‘cmd’ rather than ‘dialout’. It’s possible that the udev-rules need a little edit? Thanks for the suggestion - I’ll look at that and post back here with the result.
I have to say, the m0 boards are really nice! Once I’d got the upload going, getting two devices to exchange data over the 433Mhz link was really smooth and the current project is flying along! Dave