Restore gridliner toggle call for empty labels

Author: cvanelteren

ultraplot/axes/geo.py

@@ -2788,6 +2788,9 @@ def _update_major_gridlines(
             allow_xy=True,
             include_false=True,
         )
+        if not sides and lonarray is not None and latarray is not None:
+            # Preserve legacy behavior by calling the toggle even for no-op arrays.
+            sides = {side: None for side in _CARTOPY_LABEL_SIDES}
         if sides:
             self._toggle_gridliner_labels(**sides)
         self._set_gridliner_adapter("major", self._build_gridliner_adapter("major"))