I see similar issue. Sorting users by nested attributes returns 400 error:
{
"statusCode": 400,
"error": "Bad Request",
"message": "Failed to perform search. Make sure the query \"app_metadata.deleted:false AND app_metadata.admin:false\" is valid"
}
Also when I try to search for a nested attributes, eg. “app_metadata.deleted:false AND app_metadata.admin:false” without any sorting set does not return anything.