Index: src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
===================================================================
--- src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php	(revision 44988)
+++ src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php	(working copy)
@@ -2026,10 +2026,16 @@
 			),
 		);
 		foreach ( $post_type_attributes as $attribute ) {
-			if ( isset( $fixed_schemas[ $this->post_type ] ) && ! in_array( $attribute, $fixed_schemas[ $this->post_type ], true ) ) {
-				continue;
-			} elseif ( ! isset( $fixed_schemas[ $this->post_type ] ) && ! post_type_supports( $this->post_type, $attribute ) ) {
-				continue;
+			if (
+				( ! isset( $fixed_schemas[ $this->post_type ] ) ) ||
+				(
+					isset( $fixed_schemas[ $this->post_type ] ) &&
+					! in_array( $attribute, $fixed_schemas[ $this->post_type ], true )
+				)
+			) {
+				if ( ! post_type_supports( $this->post_type, $attribute ) ) {
+					continue;
+				}
 			}
 
 			switch ( $attribute ) {