Issue:  CashFlowTool shows $0 for both A/R and A/P.
Resolution: Check to make sure your accounting method is set to accrual basis instead of cash basis in QuickBooks.
QuickBooks Online
https://quickbooks.intuit.com/community/Help-Articles/Change-your-accounting-method/m-p/186425
QuickBooks Desktop
https://quickbooks.intuit.com/community/Help-Articles/Differentiate-Cash-and-Accrual-basis/m-p/202612