You have to switch back to the old layout. In the Invoice editing interface (open an invoice and edit) at the top right corner is an option to "switch to old layout". Click this, confirm the selection and you will be able to print packing slips again. We will all be subject to the new layout automatically on 10/16/23 according to QBO. Hopefully they create a packing slip option for the new layout by then.

Good luck.