Caused by 21aef81714
Now, pass along `uiname` as `std::optional<StringRef>` early on (and use
`std::nullopt`).
Without this, the `(!uiname || !uiname->is_empty())` condition in
`ui_item_enum_expand_elem_exec` wont be true, resulting in the empty
label.
Pull Request: https://projects.blender.org/blender/blender/pulls/135621
a568890515