Found the issue maybe?

It could be a SO to Invoice issue.   This function of coursed worked before.  

Whatever the new update QB made to Desktop 2019 on October 1st 2025, it messed with the program.  Where any Invoice coming from a SO you can no longer print or save to PDF.  That forces a lot of people to have to abandon their paid software and have to upgrade to a monthly subscription.  Great business tactic if true.  

As far as we can tell, you can still print invoices otherwise in both customers...  just can't do it through a SO now....... you can make the transaction, but just can't PDF or Print.