Need to modify invoice impacted by the invoice problem

While we’re still having the problem with invoices converted from estimates, I have needed to modify an invoice for almost a month now. I would really like to get this taken care of, so it doesn’t continue hanging over my head. I have been worried about modifying the invoice, when all of the text in the body of the invoice has disappeared. I’m concerned that I would be unknowingly add text over the text that had disappeared, because I can’t see it. How can I modify this invoice without messing up the original invoice text? 

And any news on when we can expect this to be fixed? Last I heard, I was told there’s no estimate on when it will be fixed.