Investment categories not showing up in drop-down menu

I think I understand the problem. In an investment register, there are two types of transactions co-mingled: those which have Types which are investment activities (as shown in the picture above), and those which have a Type=Payment/Deposit, which are like transactions in banking accounts. Only Payment/Deposit transactions can have categories or transfers. A Sell Bond transaction cannot have a category. (Try creating a new transaction, select Type=Sell Bond, and you'll see a Category cannot be entered.) And conversely, a deposit or payment cannot have an investment activity as a manually applied category. (A deposit transaction has no way to capture how many shares of the security were bought or sold.)

So this comes down to what was downloaded by your brokerage: whether they coded the transactions correctly or not. If you actually sold bonds, they could/should have sent such a transaction, which would reduce your bond holdings and create cash. I can't tell which columns I'm seeing in your screenshot, but it appears that they are showing only deposits of money. These are not Sell Bond transactions, which would reference the security being sold and the number of shares. Does the "Journal From 31xxxxxx" description refer to a different account the money is coming from at your brokerage? Is that an account you separately track in Quicken? 

So to recap: an investment activity like Buy or Sell is a specific type of transaction that does not have a category and uses or creates cash in your account which can be invested in other securities or transferred to other accounts. It looks like you are missing those transactions in your account, perhaps because your brokerage is reporting them as just cash deposits. Perhaps if you mention the brokerage, others here might be able to shed more light on this.