James,
I just created a test listing using the UK scheduler and it posted successfully to eBay.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=6478330255
I scheduled it at about 11:15 AM PST to go on at 12:00 PM PST today and it lauched successfully.
Perhaps you should try creating similar listings from these listings you've been trying to schedule and maybe they'll post then.
-Mike