Does anyone know whether it is possible to access the Inventory Detail history for a line on a sales order? Such as when it was set?

It doesn't show any date/time fields in Record Browser for Inv Detail record. That means that unless the System notes capture changes, it won't be possible. I'd recommend reviewing system notes on the transaction AFTER you change Inventory Detail. If it logs an audit line, you could use that from a saved search and report on it. From my experience System Notes is pretty limited. Another approach, if it works in your scenario, could be to write some type of saved search email alert that looks at the total quantity by lot/serial number - a change in the Inventory detail would trigger an alert.

Thanks for your reply and suggestions Ankur. My use case was to try and understand when and why the inventory detail on some sales orders was unset. Removing the detail at line level does not show up in the line history, so it's very difficult to track.