Enable the lock file setting
Per the Release Notes for Product Update 4 for Sage 100 2018, resolved with that update.
Per the Release Notes for Sage 100 2019, resolved in that version.
For S/O Invoice printing issue with Keep Open after Print: Paperless Office must be already set up with Forms selected and Form Maintenance configured for S/O Invoices plus Email setup in Company Maintenance and Accounts Receivable customers have email addresses set up (use an email address for customer that allows email to be sent to you). 1) Using Paperless Office, Setup, Electronic Delivery Message Maintenance add Merge fields into the Subject field (such as or) 2) Create/Choose a Sales Order Invoice Batch containing multiple invoices for customers with email addresses existing 3) Print the Sales Order Invoice Batch: a) select Sales Order, Main, Invoice Printing, select the Print check box on the Batch, and select Proceed b) on the S/O Invoice Printing window choose the following: i) Select the "Keep Window Open After Print" checkbox ii) Select a Paperless Office Output option that includes Electronic Delivery (such as Electronic Delivery Only). iii) In the Invoice Number field, select the lookup and choose the first invoice number listed in the invoice list. c) Select Print to electronically deliver the Invoice. Note: you may need to choose Print Invoices Already Printed once they’ve been printed. Processing Invoices/Sending e-mail will appear d) Once 1st invoice sends email, check the email sent for this invoice and it will show the correct email Subject information with correct invoice attachment e) keep the Paperless Office Output selection and "Keep Windows Open After Print" option and then select the 2nd invoice from the Invoice list via the Invoice lookup list. f) Print the 2nd invoice g) Once the email is sent, check the email and it will show the information from the first invoice in the subject of the email for the 2nd invoice (and others). The Invoice attached will be for the correct customer. The merge fields in email Subject aren’t updated on 2nd and later invoices printed if the "Keep Window Open After Print" box is selected AND individual S/O Invoices are printed from a Sales Order Invoice batch.