Custom grouping by m2m field is introduced here: https://github.com/odoo/odoo/pull/74985. However, after refactoring in https://github.com/odoo/odoo/pull/73311, users are unable to add custom groups based on stored m2m fields. This is because the stored m2m fields are not included in the list of "Add Custom Group" options. In this commit, we are now again including the stored m2m in the options for "Add Custom Group". closes odoo/odoo#104873 Task-id: 3046183 X-original-commit: 5087d9011be7f46a4a3e05b1e951f2556f254b4c Signed-off-by: Mathieu Duckerts-Antoine <dam@odoo.com> Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>