A strange thing has been happening with our listings: they are not ending automatically, or sometimes even after many tries!!
Since June 6, any item that has sold remains available for sale until we manually end the item. In some cases, even items that were manually ended still turn up for sale the next time we look. At this point, we're looking at over a dozen affected items, and some are still popping up as available. 
Unfortunately, there is no example listing to share as we're being vigilent, as that seems the lesser headache (than double-selling our mostly OOAK books). We've called eBay a few times, spending some number of total hours on the phone with eBay. Even after the issue was escalated (2x now), we're still not seeing any resolve. Or contact. Or acknowledgment. It seems a realistic concern that something might sell overnight while our backs are turned (or asleep), and then it might sell again before we catch it in the morning. It won't be eBay that takes the flak, but our store name.
Has anyone else experienced anything similar?
Any thoughts or suggestions are welcome!
Thanks in advance, and have a great day. 
