When entering a stock sales order and specifying lots, the available shares (including fractional) reported in the "Specify Lots Sold in This Transaction" window are more than is actually available. I discovered this after originally checking the "Sell all shares in this account" checkbox in the "Edit Sell - Shares Sold" transaction editor window, entering the "Total Sale" amount, and pressing the "Enter/Done" button. In the Holdings view for the account at a date after the transaction, I discovered a negative number of shares for this stock.
I am using Quicken 2017 Premier, Version R5, Build: 26.1.5.5
OS: Windows 7 Professional, Service Pack 1, 64-bit