The sale of Units does not create an income, it replaces one asset (investment units) with another asset (cash) and then you are using an asset to pay an expense, hence why on an I&E report you only see the expense. This is standard accounting.
If you really must show it as an income you need to create some more entries. Once way of doing this is to record the proceeds of the sale as going to a category, you might call it Investment Drawdown or something of the like, then you record another transaction for the same amount. with an income category something like Proceeds of Investment Sale. this creates the entries necessary to satisfy accounting rules and provide what you seem to be looking for.