Second taxonomy field not saving in field group

Hi everyone,

I’m working with Metabox and have created a field group assigned to a custom post type (anzeige). In this field group, I’ve added two taxonomy fields:
1. Anzeigtyp (custom taxonomy)
2. Spalten (another custom taxonomy)

Both fields appear correctly in the post editor, but only the first one (Anzeigtyp) gets saved. The second taxonomy (Spalten) doesn’t store any values when I update the post.

Here’s what I’ve checked so far:
• Both taxonomies are registered and working properly.
• The field group is correctly assigned to the post type.
• The Spalten taxonomy is not hierarchical (if that matters).
• I’m using the Bricks Builder, but even in the default WP editor the issue persists.

Has anyone run into this issue before? Any ideas why the second taxonomy field might not be saving?

Thanks in advance!

Screenshots