Your issue seems exactly like mine.

Are you certain that the Account Type for your expense transactions are setup as: Expenses, Cost of Goods Sold, etc? In my experience, your Vendor expenses must be setup with one of the expense Account Types (see attached). Any expense with Account Type: Asset, Equity, A/R, Income will not hit your Project as an Expense and therefore will not show up as a Project Cost. I suggest opening one of your expense accounts in Chart of Accounts and checking the Account Type. As a test, you could create a temporary expense account that uses Cost of Goods, Cost of Labor, Expense, etc. as the Account Type and then add a fake transaction to one of your Projects with this temp expense. Then check your Project Summary to see if it showed up as an Expense to the Project.