I've had the same thing happen twice, only I was sitting there typing in very detailed descriptions for the estimate and searching RS Means data to validate pricing. Apparently QuickBooks does not view you adding line items to an estimate as "activity." Here is the most laughable thing, the QuickBooks forum just autosaved my reply here but in the Year Of Our Lord Two Thousand Twenty, they cannot autosave an estimate to complete on re-login if they log you out!! At MINIMUM it should at least prompt you on the alledged inactivity before it screws you over. This is a severely screwed up UX. This is basic stuff Intuit. Very basic stuff to deliver a good user experience over a crappy one.