Media Library empty or only missing item(s) when invoked from custom post type set featured image button

[openmindculture]

Custom post type 'offer' is defined in a 'mu-plugin' using ACF syntax including featured image support. Theme functions also explicitly declare featured image support for this custom post type.

When invoked from main wp-admin sidebar menu, the media library shows multiple image items. But when invoked from custom post type set featured image button the library either claims that it's empty or it contains exactly 1 image, the one uploaded for this post.

After uploading a new image into a seemingly empty library invoked from a custom post, this image shows in that media library view, but also in the full list when invoked from the wp-admin sidebar menu.

This happens with or without using image optimization plugin like TinyPNG.

WordPress version: 6.3
Advanced Custom Fields version: 6.2.0

[openmindculture]

Asked on wordpress.org: https://wordpress.org/support/topic/media-library-empty-or-only-1-item-when-invoked-from-custom-post/

[openmindculture]

Asked on wordpress.stackexchange: https://wordpress.stackexchange.com/questions/418213/media-library-empty-or-only-1-item-when-invoked-from-custom-post-type-set-featur

[openmindculture]

Workaround:

• deleted all images in the WordPress media library UI
• deleted the remote directories and ensured write and read permissions on wp-content/uploads
• upload each image where it belongs, one after another
• await external hints and solutions

[openmindculture]

Mistakenly reported or changed behavior, as I now start by uploading all the images for the offer post type:
now it seems that the posts only show those media library items

• uploaded for posts of the same language
• (and probably also of the same (custom) post type)?

[openmindculture]

Todo: verify if this correlates to custom post types or rather to multiple languages which would make it a Polylang (configuration) issue.

[openmindculture]

can't reproduce anymore?

[openmindculture]

Possibly a bug, misfeature or misconfiguration of Polylang?

Current behavior:

After uploading a new image as a post thumbnail and saving the post, this very image is not available to choose as an existing image item in the media library when adding a translated post version in another language. So I have to upload the same image again. This makes me and my customers upload every image 2 times, as we have 2 languages.

Possibly related existing issue: https://wordpress.org/support/topic/images-not-showing-in-one-of-the-languages/

New issue: Support: Plugin: Polylang: Media Libray images only showing in one language:
https://wordpress.org/support/topic/media-libray-images-only-showing-in-one-language/