When you say,"Listings disappearing" are you saying the listings are no longer in your active listings? or are you saying the listings are not visible to buyers in your store or in search results?
If you are saying they are no longer in your active listings check your unsold. Ebay had some issues with item specific being changed and mandatory item specifics which were new was causing listings to be ended. For the most part this was with clothing but I think someone mentioned sports memorabilia being effected.
Check your unsold and little by little you may want to go through all of your listings to make sure the item specifics are correct.
