I was able to add my estimates without issue. 

I simply went into my estimate and selected the project name. 

Then, in the project tab under "Transactions" tab the estimate was added. 

One thing i did note, once you add your estimate in the project, NOTHING CHANGES. You won't see anything in the "Income vs Cost" bar graph. You will only see these values fill out once you actually convert the estimate to an invoice (or migrate invoices into the project)

For some reason, the dashboard does not have any indication of the estimate at a glance. you have to go to the Transaction tab to see your estimate. The entire Projects tab seems to function only on invoices billed to date. And it does not seem to take into account what your balance to finish is. 

Im also very new to QBO so maybe i'm missing something, or have a feature turned off.