Update (just in case someone should encounter the same problem)
After a deep search and nothing found I remembered I’ve had the same problem with Firefox: no audio from YouTube on my interface, just from the built in speakers. So I did a search in that direction and I found out my guess was right: the problem is the internal audio signal routing. I remembered I had an application called Soundflower, now evolved into Loopback, that allows to “see” and also modify the signal path. You can save different configurations and recall them according to your needs. Settings can be saved and will stay there, so no need to keep the application open.
I just changed the output from Main Out to SPDIF, which is the one I use.
Everything works fine now. Problem solved.
thanks for your reply. Yes my audio interface shows up everywhere it should and works fine with every other application. The problem is FCPX doesn't "see" it. It only sees the built in output.
As far as the button for plugins rescan, how can I know which option is selected? I mean, let's say I pushed the button once, and the next time I want to undo that, how do I know what option's been chosen last?
and congrats for this great site. I'm not a video editing geek, but I have used fcpx 10.1 for a quite long while with no major issues, being my editing work very basic. I recently upgraded my OS to HighSierra and I had to upgrade fcpx too. The version I use now is 10.4.6 and since its installation I had lots of problems: first, i had to take off all my AudioUnits cause the application took 30 minutes to open, doing an endless "au validation" process at every start (there's an option to choose whether or not to scan the plugins, but the drop down menu doesn't drop down, so the only choice is "rescan every time".
The major issue is anyway the audio output. I have a MOTU 828 mk3 FW, which I always used as my audio interface.
What happens is: I see meters flashing green, but I don't hear anything. The only way to hear something is to choose the built in audio. It looks like the application doesn't recognize the interface, which is strange cause in the CueMix I can see the meters active (attached screenshot). I did a three day research but I find nothing about it. It seems there's no way to manage the audio routing in fcpx.
-iMac 27, mid 2011 - HighSierra 10.3.6
-MOTU 828 mk3, latest drivers and firmware
-The problem persists on every whole project, not a clip problem.
-All the projects and libraries worked fine with no adjustments in fcpx 10.1
Any help would be greatly appreciated. Thank you.