I just saw today that rc.26 has gone. The old method to increase a version was to select the version and install an .ino. (Careful you couldn't go back to an old version without a full factory reset, not sure if that has changed) If your photon was at the top of the list (default) then every time you installed an .ino the Photon would update if needed. This was a huge problem with bad Wifi, so I would often pick a version and have my class set every photon to that version, then if a new version came out I would test it, switch briefly to default update every photon and then switch to that version instead of default. Only because of bad wifi. The Argon seems to handle my school wifi better than the Photon so that might not be a problem now.
So Last night I tried to setup my 1 Argon and 3 Xenon network and I got the Argon working but the 3 Xenon's just flashed green. This morning I tried again with the Argon which worked, but the xenons didn't (just flashed green). I updated and installed a 4th Xenon and not really sure when but the old Xenons started working. Briefly I had all 4 Xenons breathing cyan.
About 5 minutes later all my Xenons are flashing cyan which I think means they have lost the Mesh, Argon stable. Will leave things for a while and see what happens.
Note: Not having much luck with adding multiple Xenons to one Argon with the app, after adding a Xenons it says do you want to add another. This has not worked well for me. If you have an issue it kicks you out of the add another so I have resigned myself to add each xenon individually.
P.S. I would be great if the app allowed multiple steps. On step to update a device, another step to assign Wifi and another step to Add Mesh devices to a mesh network. I am always starting from scratch, have entered my home Wifi password multiple times. Also since most laptops have Bluetooth it would be nice if there was a web or windows desktop app to do all this installing. I seem to remember some kind of web softapp for the photon.