AP-25288: Fix behavior for filters that contain only invalid members

Co-authored-by: Copilot <[email protected]>

Author: AtR1an

org.knime.python3.nodes/src/main/python/knime/extension/parameter.py

@@ -1774,14 +1774,14 @@ def _get_visible_options(self, dialog_creation_context):
                 f"{invalid_members}. Valid options are: {valid_options}"
             )
 
-        # If all members are hidden or all returned members were invalid, show empty
+        # If all members would be hidden or all returned members were invalid, fall back to showing all
         all_members = list(self._enum)
         if len(validated_members) >= len(all_members):
             LOGGER.warning(
                 f"hidden_choices for parameter '{self._label}' would hide all options. "
-                f"Showing empty options."
+                f"Showing all options instead."
             )
-            return []
+            return all_members
 
         # Return members that are not in the hidden list
         hidden_names = {member.name for member in validated_members}