Okay, not completely fixed. I had a crash today and it appears my Custom List View Layout has gone bye-bye. Does anyone know how to change the current (stupid) default to my own default. (I said stupid because, in my case, 360˚ Mode & Stereoscopic Mode, which are ever present and cluttering my list, are not something I need showing all the time.)
Reported to Apple's FCPX team.
The administrator has disabled public write access.