This always happens, everytime eBay did any changes, they wipe out all accumulated best match searching credits on your listings, make them start over again. Especially when they redo the indexing on thier database. This happens over and over last year, and same thing this year.
eBay simply just can not keep up with themselves. They have to restructure their database to accomodate the new rules, wipe out all the old existing credits is the easiest way to do, and without letting you know, so you can't even complain, nor prove it. The only thing you can wonder is how come all your sales drop tremendously and how come your listing can not be found in the search result ? My eBay listing has over 50% now have no viewing history at all.
If I could rate eBay's DSR (business pratice), it will be 1 star all the way, which make eBay a limited seller by their own standard.