"Although this list item is inactive,"
Open your Items List. At the bottom, Checkmark "Include Inactive." Now you see everything.
"maybe it was used on an Estimate but since that doesn't show on the QuickReport I can't find which Estimate"
Or, you likely have this inside a Group Item or an Assembly Item from Builds.
Or, a Service Item is in use on Timesheets. It is easy to see this, but you need Other Reports.
Reports menu > Jobs, Time and Mileage.
Examples: Time by Item. Item Profitability. Estimates vs Actuals Detail.
Or, you used a Charge item in a Mileage entry. Run the Mileage reports, from here.
