Why doesn't FCP x 10.4 utilize the processors when rendering and exporting

I'm using Final Cut Pro x 10.4 on a brand new Touch Bar MacBook Pro - one of the main reasons I upgraded to the latest MacBook Pro was to get the fastest possible processors for rendering and exporting in FCP. But it is essentially no faster than my old 2011 MBP or my 2012 work MBP, primarily because FCP is only using 1/5 to 1/4 of the processing power. I don't see any settings in the preferences to fix the issue or to have caused the issue. I want to see FCP using every bit of my processors on both renders and exporting.

I'm primarily rendering color fixes. For exporting I'm usually compressing 1080P to 720P after trimming a basic clip.

Anyone know of a way to get FCP to utilize the processors I've paid for?

Latest MBP touch bar 2.9 GHz i7, Radeon Pro 560 4GB video card, OS 10.13.3, FCP 10.4