fix(SelectPanel): do not depend on id for selection comparison

.changeset/fluffy-squids-hug.md

@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+fix(SelectPanel): do not depend on id for selection comparison

packages/react/src/SelectPanel/SelectPanel.tsx

@@ -391,11 +391,13 @@ function Panel({
       // For single-select modal, there is an intermediate state when the user has selected
       // an item but has not yet saved the selection. We need to check for this state.
       if (isSingleSelectModal) {
-        return intermediateSelected?.id === item.id
+        return intermediateSelected?.id !== undefined
+          ? intermediateSelected.id === item.id
+          : intermediateSelected === item
       }
 
       // For single-select anchored, we just need to check if the item is the selected item
-      return selected?.id === item.id
+      return selected?.id !== undefined ? selected.id === item.id : selected === item
     },
     [selected, intermediateSelected, isSingleSelectModal],
   )