Why is the tag not added to order?

If a tag is not added to an order, it's because the order's information doesn't match with the condition you set.

First of all, copy the order's ID whose you think the tag should be added to Secondly, select the tag that you think it should be added to the order Finally, put the order's ID to the test field and see does it matches or not

Please refer to this video for a tutorial