There are a few very obvious issues with QB. I can't even imagine looking at the code, it must be a complete mess, hence why you can't do a quick fix on a lot of issues. Intuit doesn't have that much of an investment in fixing the issues, because as the gold standard people are going to use it regardless of the bugs.

Here's one, for example, when you add a new project, you can't access the project in an invoice until closing and restarting the program. Which probably means you're not using a generator for the list. Or something.