If it makes you feel any better, I have Quickbooks Desktop 19 for Mac.  I have NEVER updated the software to a newer version, but I am still being locked out of importing QBO files.  It seems illegal the Intuit has sent some data to my purchased software (without my knowledge, or consent) and basically made my software purchase obsolete.

So I don't think you updating to the latest version had any effect, even without accepting an update they've managed to rip-off their customers!