Unfortunately, it seems like QB techs are dealing with a lot of antiquated systems from the 90's and early 2000's and it's understandable that they can't fix things. There's literally no way for them to do that aside from actually making a new version of Quickbooks Desktop.

It's been almost 15 years since that has happened. What you are using now is basically the husk of what we had in the late 90's and the strain of the database can be heard all across the world.