For me using "enable-blink-features=ShadowDOMV0 --enable-blink-features=CustomElementsV0" for newer Chrome or using older Chrome version did not work.
However, using older Chrome: "Version 79.0.3945.0 (Developer Build) (64-bit)" AND putting the following in config.xml seemed to fix Web Inspector:
<access origin="*" subdomains="true"></access>