So I have the most recent Wordpress ~6.4 and have a Multisite set up. The template loads the ACF options page like this:
private function __construct() {
/** OTHER ACTIONS & FILTERS **/
if ( function_exists( 'acf_add_options_page' ) ) {
acf_add_options_page();
acf_add_options_page( 'Admin Options' );
}
}
Now the "Admin Options" page works on a single instance, or if the Multisite Subsite is the first/main installed site. As soon as it is not I get this errors:
Meanwhile the "normal" options page, works on every single instance I have tested.
To my knowledge I have nothing that could interfere with the "Admin Option" page. Also, the ACF fields settings are clearly correct:
I set up multiple single and multisites, each of them with the same result/issue. Single sites always work. On multisites "Admin Options" always work on the main-multisite. Not on any of the subsites.
Removing all my code, except the function i have above, did not change the result. Still no "Admin Options" page fields.



As usual, within a short time of posting a question, the answer comes:
So turns out that Multisites in Wordpress don't just have "Administrator" but actually a "Super Admin" too. ACF does not seem to have the option to select "Super Admin", so i removed the ACF rules and refactored my code to do it via PHP like this: