EditorDescriptorRegistration not triggered

CMS 11

Hello! Ive got a plugin out there with an EditorDescriptor, but it is not triggered in ONE implementation. What can it be?

yes there is other descriptors in solution with TargetType = typeof(XhtmlString) and they are triggered

 [EditorDescriptorRegistration(TargetType = typeof(XhtmlString), EditorDescriptorBehavior = EditorDescriptorBehavior.PlaceLast)]
public class XhtmlStringEditorDescriptor : EditorDescriptor
{
        public override void ModifyMetadata(EPiServer.Shell.ObjectEditing.ExtendedMetadata metadata,
            IEnumerable<Attribute> attributes)
        {
            //no breakpoint triggered here
            if (metadata.EditorConfiguration["settings"] is Dictionary<string, object> settings)
            {
               //some code here but gets never hit
            }            
        }
}