Hello jedrolfe!
Thanks for joining this thread. Let me assist you in running the report you need.
I know that QuickBooks Online doesn't have an Average Days to Pay report. Currently, this is only available in QuickBooks Desktop. You'll want to follow the workaround shared by my Giovann_G and JessT, by running the Invoices and Received Payments report.
Also, our engineers keep on updating QuickBooks Online to meet the needs of every business. You'll want to send feedback and let them know that you want the Average Days to Pay report to be added in QuickBooks Online. Go to the Gear icon and select Feedback.
Although a feature request has been sent, we're unable to determine when it'll be implemented. However, it's most likely to be prioritized if our team received more requests about it.
I added this link if you need help in running, customizing, and saving financial reports in QuickBooks Online: Run reports in QuickBooks Online.
Please know that you can always post here if you have other concerns. Stay safe!
