Thank you for posting here in the QuickBooks Community, @amper. 

I understand how important it is for the expenses to show on the project summary report. Allow me to share additional insights about Project Summary reports in QuickBooks Online.

It can be that the expense transactions were not marked as billable to the project. Make sure to review the Expenses you'd want to check if they are billable regardless of if they are on an Accrual or Cash basis.

We can review this by opening the transactions. Just go to the Projects page, then select the project and look into the Transactions tab to open one and check the Billable column. 

I'm adding this article about the Projects feature in QuickBooks Online: Track income, costs, and profitability by the project.

If there's anything else you need help with the project, let me know by adding a comment. I'm always here for you. Have a good one!