I am not able to see GSTIN number of my company on the invoice when the Invoice is created with Services which are "Out of Scope" from tax. The same is visible when the invoice is created "Exclusive of Tax".
With regards to your query, we request not to select the tax code "Out of Scope" but, please select the tax code 0% IGST or 0% GST whichever is applicable. So that, GSTIN will show on the invoice.
Please do call us on our helpline number.
Hope this helps