@Crell Don't know if this helps Larry, although I had this in WSL, it's still *nix based, so maybe relevant?

https://www.squarecone.com/phpstorm-cannot-find-vendor-autoload-php-on-docker-wsl2-when-running-phpunit

With the likes of phpstan etc, I always have to configure it specifically, using "default interpreter" doesn't work for me, but selecting the configured interpreter works (I have the same issue with the other quality tools.. cs-fixer, etc).

Don't know if you've tried this.. apologies if you have.