on jmix 1.2.2, helium extended theme with no customization (just for branding), datagrid loads rows but displays no text in cells.
EDIT: just created new Jmix project, and changed the default created groupTable en Users browser sceen to a datagrid, same result.
EDIT 2: found the issue, maybe this helps some body: the default table generated by JMIX Studio does not add property tag for columns, just id. Somehow thats sufficient for table but datagrid requires property tag. After changeing id for property it work as expected.