diff --git a/sources/zarr/large_image_source_zarr/__init__.py b/sources/zarr/large_image_source_zarr/__init__.py
index 58285fd51..3103077d1 100644
--- a/sources/zarr/large_image_source_zarr/__init__.py
+++ b/sources/zarr/large_image_source_zarr/__init__.py
@@ -507,13 +507,22 @@ def getMetadata(self):
                     all_frame_values = self.frameValues[..., i]
                     split = np.split(all_frame_values, all_frame_values.shape[i], axis=i)
                     values = [a.flat[0] for a in split]
-                    uniform = all(len(np.unique(a)) == 1 for a in split)
+                    uniform = all(len(np.unique(
+                        # convert all values to strings for mixed type comparison with np.unique
+                        (a[np.not_equal(a, None)]).astype(str)
+                    )) == 1 for a in split)
+                    try:
+                        min_val = min(values)
+                        max_val = max(values)
+                    except TypeError:
+                        min_val = None
+                        max_val = None
                     result['Value' + axis.upper()] = dict(
                         values=values,
                         uniform=uniform,
                         units=self.frameUnits.get(axis) if self.frameUnits is not None else None,
-                        min=min(values),
-                        max=max(values),
+                        min=min_val,
+                        max=max_val,
                         datatype=np.array(values).dtype.name,
                     )
             for idx in range(self._framecount):
@@ -810,7 +819,10 @@ def _getAxisInternalMetadata(self, axis_name):
                     all_frame_values.shape[axis_index],
                     axis=axis_index,
                 )
-                uniform = all(len(np.unique(a)) == 1 for a in split)
+                uniform = all(len(np.unique(
+                    # convert all values to strings for mixed type comparison with np.unique
+                    (a[np.not_equal(a, None)]).astype(str)
+                )) == 1 for a in split)
                 if uniform:
                     values = [a.flat[0] for a in split]
                 else:
diff --git a/test/test_sink.py b/test/test_sink.py
index fc146628d..1a3ef8c7d 100644
--- a/test/test_sink.py
+++ b/test/test_sink.py
@@ -743,3 +743,12 @@ def testFrameValuesEdgeCases(tmp_path):
     ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=1, z=2, z_value=6.4, c_value='CD4')
     ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=1, z=1, z_value=3.1, c_value='CD4')
     ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=0, z=1, z_value=1.1)
+
+    ts = large_image.new()
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=0, z=0, z_value=1, c_value='DAPI')
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=0, z=1, z_value=3.2, c_value='DAPI')
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=0, z=2, z_value=6.3, c_value='DAPI')
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=1, z=2, z_value=6.4, c_value='CD4')
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=1, z=1, z_value=3.1, c_value='CD4')
+    ts.addTile(np.zeros((100, 100, 3)), x=0, y=0, c=0, z=1, z_value=1.1)
+    assert len(ts.metadata.get('frames', [])) == 6