It appears the IRS has discovered that I did in fact file my taxes in 2006, just like I thought I had. They have, however, now moved on to a new and weirder problem.
They’re now notifying me that they want to see the records of my expenses and income from all the rental property I own. Specifically, they want me to fill out a form showing my total combined income from all my rental properties, together with itemized expenses for maintenance, repairs, and advertising for those rental properties.
I have never in my life owned rental property. This is just getting bizarre.