But need to investigate why $custom_fields['ip_invoice_custom'] is not set here.

And other little bug with this field settings page -> Invoices tab -> Enable Qr code option -> select#tags_invoice
always set with ID (never saved (or selected?))
and (after added an Invoice custom field) this is not listed (TEXT field in my case).

@nielsdrost7 Maybe for IP-1.6.3 ;)

Follow-up of #1163