Activa is now flashing an INFO banner alert on the main page on this problem. If you click on it, you get this pop-up:
"Users who posted listings to eBay between 2:00 pm and 6:00 pm PST on Sunday may notice a delay in their postings. We have addressed the issue and your listings will post normally with no further action required from you. We apologize for any inconvenience or confusion caused by this delay."