Sometimes when running composer install
for Magento 2 depending on your current directory structure the Magento composer plugin does not extract/copy the files out of vendor.
Which leaves you with a broken installation.
curl -s https://gist.githubusercontent.com/adamzero1/0eb6d3e14078676a3ba589d77ba67b3d/raw/6ed67290b6eca7211942d1363ab6115eefd590a6/fix | bash