Hi @ian, welcome to the DevKinsta community!
Thanks for sharing the troubleshooting you have done so far, that quickly lead me to find the culprit.
What defines whether a site is listed as a “custom site” vs. a WP site?
We use a specific WP CLI command to verify that WordPress is installed and that it isn’t returning an error. When this command isn’t able to return a standard response, DevKinsta uses the label “Custom site”.
I was able to replicate that DevKinsta shows “Custom site” when the Acorn plugin is installed as a mu-plugin. This is due to the fact that when not installed as a regular plugin, Acorn is returning a critical error regarding the PHP version being used as it checks the CLI version of it via Composer instead of checking the FPM version (which is set in DevKinsta and that can be easily changed).
You can verify this on your side too, if you are familiar with Docker, by using this command inside the devkinsta_fpm terminal after moving to the site location:
wp core is-installed --allow-root; echo $?
The error returned should then be:
PHP Fatal error: Composer detected issues in your platform: Your Composer dependencies require a PHP version “>= 8.0.2". You are running 7.4.30. in /www/kinsta/public/yoursitename/wp-content/mu-plugins/acorn/vendor/composer/platform_check.php on line 24
Fatal error: Composer detected issues in your platform: Your Composer dependencies require a PHP version “>= 8.0.2”. You are running 7.4.30. in /www/kinsta/public/yoursitename/wp-content/mu-plugins/acorn/vendor/composer/platform_check.php on line 24
Error: There has been a critical error on this website.Learn more about troubleshooting WordPress. There has been a critical error on this website.
So, as explained above, since that WP CLI command isn’t returning 0 as response, DevKinsta shows “Custom site”.
If you really want to solve that, you will need to manually edit the PHP version used by the command line. This can be done by running the following command and selecting the preferred version (in this case, 8.0 or 8.1) inside the same docker terminal:
update-alternatives --config php
Once this has been done, DevKinsta should then change “Custom Site” to “WordPress x.z.y” where x.z.y is the version used.
I hope this helps!