OMG! Thank you for posting this. The issue was that the number of shares in each lot wasn't carried forward even though the software already had the answer on another screen—within the same workflow! Once I entered the number of shares into any field wanting it, the errors went away. I ignored the fact that those fields were blank because nothing else on that screen was relevant for me, so... I assumed that.. the reason the fields were blank was for this very reason. Why would it need the number of shares on that screen if none of the calculations on that screen were relevant? But... behind the scenes, the code is still expecting these fields to have values. This is why it's a bug, and why it should be CRIMINAL to not fix such bugs.
Think about it: if you can't figure it out, what are you going to do? Ask someone for help—right? And, often, that help costs money. So... it's criminally negligent to not fix these bugs, IMO.
As a Product Designer working in the SaaS industry... this is absolutely SHAMEFUL that Intuit hasn't caught or fixed such a bug. I became violently angry on so many occasions while trying to figure this out, and have spent several hours trying to do so.
Filing one's taxes is a financial activity... with significant legal implications... any company profiting from the "tax" industry certainly has an obligation to fix all known bugs—especially a company like Intuit, which has spent millions lobbying congress to keep the tax code and tax filing procedures from evolving in a way that might threaten their profits.
They have an obligation because people's lives can be severely impacted by filing incorrectly, or by filing in a way that prevents them from getting the tax refund to which they are legally entitled. Financial institutions aren't required to do things that would make filing your tax return easier.. even though they could do so very easily.
