Bought 5th wheel from private seller with lien - problems

I've never heard of the USPS losing a certified letter but I guess anything is possible. Glad that you are past the big issue of where's the money, and a big relief that it's just lost and not being spent by the seller.

Worst that will happen is you delay your travels until this snafu gets straightened out, but at least you're not out any cash. A good lesson for anyone purchasing any kind of used vehicle, RV or anything else with a title.