I see now that I use 2.8.17, and not 2.8.10.
Custom post types works normally with custom fields. The one I have a problem with is an extended post type, for Download manager version 3.2.41 (W3 Eden)
Just to test I did extend the default WP Post with a text field and added an auto template to it. It loads the template and displays the field. I also tried to simplify the template for the download manager with just one of the text fields, but still it won’t load.
Following console errors without Site Kit.
JQMIGRATE: Migrate is installed, version 3.3.2 jquery-migrate.min.js:2:709
Source map error: Error: request failed with status 404
Resource URL: https://DOMAIN.COM/wp-content/plugins/download-manager/assets/bootstrap/js/bootstrap.min.js?ver=5.9.3
With Site Kit enabled these messages appeared in addition to the ones above.
This page is in Quirks Mode. Page layout may be impacted. For Standards Mode use “<!DOCTYPE html>”. ads
Content Security Policy: Ignoring “'unsafe-inline'” within script-src: ‘strict-dynamic’ specified
Content Security Policy: Ignorerer “https:” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “http:” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “'unsafe-inline'” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “https:” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “http:” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “'unsafe-inline'” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “https:” innenfor script-src: ‘strict-dynamic’ spesifisert
Content Security Policy: Ignorerer “http:” innenfor script-src: ‘strict-dynamic’ spesifisert
WEBGL_debug_renderer_info is deprecated in Firefox and will be removed. Please use RENDERER. 6kAZB2R2IkMw87P0-iGviT-Bq_noDLkkkR6BhhZ9kEI.js line 1 > eval line 397 > eval line 1 > eval line 1 > eval:1:118
I do get the same errors on Post where the template is loading.