fix reshaping of condition in where - only do for 2d blocks

Author: jorisvandenbossche

pandas/core/internals/blocks.py

@@ -1222,7 +1222,7 @@ def where(self, other, cond) -> list[Block]:
         -------
         List[Block]
         """
-        # assert cond.ndim == self.ndim
+        assert cond.ndim == self.ndim
         assert not isinstance(other, (ABCIndex, ABCSeries, ABCDataFrame))
 
         transpose = self.ndim == 2
@@ -1688,7 +1688,12 @@ def where(self, other, cond) -> list[Block]:
                 if isinstance(self.dtype, (IntervalDtype, StringDtype)):
                     # TestSetitemFloatIntervalWithIntIntervalValues
                     blk = self.coerce_to_target_dtype(orig_other, raise_on_upcast=False)
-                    if isinstance(orig_cond, np.ndarray) and orig_cond.ndim == 1:
+                    if (
+                        self.ndim == 2
+                        and isinstance(orig_cond, np.ndarray)
+                        and orig_cond.ndim == 1
+                        and not is_1d_only_ea_dtype(blk.dtype)
+                    ):
                         orig_cond = orig_cond[:, None]
                     return blk.where(orig_other, orig_cond)