If there's a mixed-attribute on the node, this will fail, just skip it

with a warning.

openpype/hosts/maya/plugins/publish/collect_look.py

@@ -549,6 +549,11 @@ def collect_attributes_changed(self, instance):
                 if not cmds.attributeQuery(attr, node=node, exists=True):
                     continue
                 attribute = "{}.{}".format(node, attr)
+                # We don't support mixed-type attributes yet.
+                if cmds.attributeQuery(attr, node=node, multi=True):
+                    self.log.warning("Attribute '{}' is mixed-type and is "
+                                     "not supported yet.".format(attribute))
+                    continue
                 if cmds.getAttr(attribute, type=True) == "message":
                     continue
                 node_attributes[attr] = cmds.getAttr(attribute)