In one case, the seller told the buyer that the property had a homeowner exclusion which allowed for a discounted rate. Turns out that wasn't true. Homeowner exclusions are generally processed once a year by the tax assessor. Miss the cycle and you pay more tax. This buyer can apply for the exclusion but got stuck paying for the extra tax for at least this year.
In the other case, a buyer of a condo in a converted building just received a bill from the tax assessor for a catch up period back to the conversion. This assessment change was pending at the time of the sale but it's not determined if anyone knew who could have informed the buyer.
In both cases, the buyers were careful when they closed. It's hard to say if either case is worth pursuing the seller or filing a claim against title insurance. It doesn't cost anything to try a claim, however, title insurance does not cover tax bills that are not yet due and payable. A case would have to be made that the title agents had evidence in hand before closing that these taxes were incorrect or incomplete information.
I wish these homeowners much luck and am posting their situations just to keep you all informed about things that can and do happen.