Final Cut Pro keeps crashing

You have that creepy cleanmymac thing - better known here as "brickmymac".

Completely uninstall this ****.

You have chrome and its evil "keystone" minions. They break video applications by mindlessly hogging the system videotoolbox. See https://chromeisbad.com for an explanation of what they and how to completely remove them.

After doing the two fixes above, drag FCP to the trash, and download a fresh copy from your account at the App Store.

Also:

Plugins:

BluRayH264Encoder - /Applications/Final Cut Pro.app

FxAnalyzer - /Applications/Final Cut Pro.app

DolbyDigitalEncoder - /Applications/Final Cut Pro.app

I am not familiar with these plugins. If they are old, maybe you need to update them.

What's the render problem? Can't guess.

Please post an EtreCheck report https://etrecheck.com giving the application Full Disk Access in Privacy System Preferences. Copy the report and use the Add Text button to paste the result into reply box. 

Joseph, did the suggested fixes make a difference in your FCP crashing? I'm having the same issue.