Hi @h6409,
If I understand correctly, you have activated the phone number displaying, located in WooCommerce > PDF Invoices > Documents > Invoice > Display phone number, in a later stage, right?
Please note that documents created before applying a specific change in the plugin’s settings, will not follow your new settings, because we stored the existing settings at the moment of the order placement per-order basis for historical reasons. For instance, if you change your shop address in the future, it should not affect old PDF invoices that you generated when your store was located in the old address.
That said, if you are just playing with the plugin configuration, or this is a new installation, you could try to activate the “Test mode” temporarily, under WooCommerce > PDF Invoices > General > Test mode. See Show PDF documents with the latest settings.