This is te info of my current setup:
-Roon 1.2 (build 157 stable) 64 bit
-Mac Pro 2010
-OS X 10.11.6
-Processor 3.33 Ghz 6-Core Intel Xeon
-Memory 32GB 1333 Mhz DDR3 ECC
-Airport express 1st gen (with latest firmware 7.6.7)
I’m running Roon in this machine and my music is in an internal HD.
The mac pro is attached to a router through ethernet and is in the same lan as the airport express.
Everything was running fine until I choose the airport express as an audio zone with the remote app installed on an iphone, at first it worked but there were some sound drops and glitches so I tried to see if there were more configuration options on the roon client on the mac pro. I selected another zone and then selected the airport express again, that moment the app crashed and couldn’t be launched again. Is as the airport express was ‘locked’ in Roon and it prevented to run.
I tried to restart Roon, restarted the Mac and finally uninstall and install Roon again with the same results.
The last thing I tried is to unplug the airport express so it couldn’t be funded and it seemed to do the trick. Roon could be launched and I select another audio zone (an apple tv) and everything was fine.
I replicated the problem, plugging the airport express, selected it in Roon and it crashed again preventing it from choosing another region.
So finally I gave up configuring the airport express as an audio zone, in fact I disabled it, and now everything is fine. The strange thing is that at least once the airport express was working with Roon, before I tried to configure it with in the Mac.
Hope this helps!