The transaction journal does not use the billable expense amount for COGS

That can happen if the item used was an inventory item.  Inventory items are stocked and then sold.  FIFO, first in first out means the oldest purchase and its cost is used, marking it billable does not change that

There were zero on hand prior to this purchase and sale.

Thanks for coming back, DonnaSanchez.

Normally, the inventory COGS is only affected when you sell inventory items on invoices or sales receipts. As what 

Rustler said the inventory items are stocked and then sold.  Then, first in first out means the oldest purchase and its cost is used, marking it billable does not change. That's why only $85 is showing in QuickBooks Online (QBO) instead of $95. For more details about FIFO, see the What is FIFO and how is it used for inventory cost accounting? article. 

To calculate the cost of goods sold, we add the cost of inventory at the beginning of the year to purchases made throughout the year. Then, subtract the cost of inventory remaining at the end of the year and the final number will be the yearly cost of goods sold for your business. To learn more about this one, see the Cost of goods sold: How to calculate and record COGS article. 

Feel free to visit our Set up inventory page for more insights about setting up items you purchase and sell in QuickBooks.

I'm just one post away if you need a hand with running inventory reports o any QuickBooks related. I'll be here to ensure your success. You have a good one.