Any joy on finding out why this is happening?

My regular customers have never had an issue in the past but now have trouble viewing invoices  they are using the same methods they have always used but over last week or so nobody can view my invoices.

I Sent them all to myself to test and I can download and open them all, so I am very confused as to the cause.

This is very unprofessional of Quikbooks to not confess to an issue they have with they app and try and pass the buck.

Hurry up with a fix please