Featured image not saving/removing for a specific taxonomy term

I’m working with a custom post type sessie that has a taxonomy soort-activiteit. For most terms, the featured image can be saved and removed correctly through WordPress.

However, when the taxonomy term is workshop_studiedag, the featured image behaves differently:

• If I set a featured image and then assign the term workshop_studiedag, the image sometimes gets cleared automatically when saving.
• If I already have a featured image set and switch the term to workshop_studiedag, the image stays in place, but I can no longer remove it.

From debugging, I can see that acf-frontend-form-element triggers the acf/pre_update_value/type=featured_image filter and tries to update _thumbnail_id with an empty value whenever the term is workshop_studiedag. This causes the thumbnail to be overwritten with null.

[11-Sep-2025 08:32:40 UTC] SESSIE SAVE START: post_id=28613, update=1, terms=[workshop_studiedag], thumb_before=28842
[11-Sep-2025 08:32:40 UTC] SESSIE SAVE END: post_id=28613, thumb_after=null
apply_filters, _acf_do_save_post, acf_update_values, acf_update_value, apply_filters('acf/pre_update_value'), WP_Hook->apply_filters, Frontend_Admin\Forms->pre_update_value, apply_filters('acf/pre_update_value/type=featured_image'), WP_Hook->apply_filters, Frontend_Admin\Field_Types\featured_image->pre_update_value, update_metadata, apply_filters('update_post_metadata'), WP_Hook->apply_filters, {closure}

It only when the Frontend Admin plugin is active. so the plugin treats it as empty and either wipes the value or doesn’t process a remove action.

Question:
How can I configure Frontend Admin (ACF Frontend Form Element) so that:

• The featured image field does not overwrite the existing thumbnail with an empty value when the field is hidden or not in the form, and
• The featured image can still be explicitly removed when needed?

• This topic was modified 2 months, 3 weeks ago by michiel1000.
• This topic was modified 2 months, 3 weeks ago by michiel1000.