Thanks for all the feedback on this issue. I tried every fix, mentioned here and on Larry Jordan's site. Nothing seemed to help, until I read about the bluetooth connection. I had been using Powerbeats bluetooth headphones for the rough cuts so I don't bother anyone else.
When I switched to powered/connected speakers (Klipsch), the problem went away. Just finished two days of editing a two hour program, and not a single non-responsive event as before. Only time I had to force quit was when the beachball kept spinning for over 5 minutes during creating a composite clip of a 1 hr segment.
Thanks again for all the suggestions.
Thanks for the suggestions. I had tried everything on the list, except trash/reinstall FCPx. Just trashed & re-installed FCPx from the App store. Problem still persists.
Updated to OS 10.14.5, even though not a good idea during a project. NaDA!
I logged all the unresponsive events today: 10 no-response events in 2.5 hours. As soon as I quit/ restart FCPx, everything works like usual. Best= 29 mins, worst=8 mins before the app stops responding to play commands. I can still click around, select clips, change settings, almost anything I want to do, except get the playhead moving - in the timeline or the browser using the keyboard or menu commands. Audio files, Video/audio, or video only. No response to space bar, menu or J, K, L
I can click on the timeline to move the playhead to the clicked position, but can't make it play.
All I can think is that I installed DaVinci Resolve 16 a week ago, and started experimenting with it because of all the good reviews out there.
Perhaps Apple is jealous?
If I ever get to finish this current project, I'll be seriously considering Resolve.
FXPX 10.4.6 on MBP OS10.14.4. Project loads in OK, editing a 2 cam multiclip works smoothly, and then after about 10 minutes or a handful of edits, abruptly stops responding to space bar, or Cmd L or J. Nothing moves. Only workaround is quitting, and then restarting FCPX. Same scenario - works fine for while, and then stops responding.
Been using FCP since v.1.0, all through fcp 7.0 and FCPx. Been editing since early 80's on NLEs.
Edited a 2 hour show on the same exact hardware/software (with the exception of upgrading to 10.14.4, with footage from the same acquisition sources, only a month ago, with no apparent problems.
Anyone have any insights?
I am getting tired of quitting FCPx every 10-15 minutes. It's getting old pretty quickly.