Technically speaking, the Global Shipping Program has never been available to Canadian sellers. You've been able to use it since you list on .com and your listings state that you ship from New York state. You might even have your eBay registration data on the .com servers rather than the .ca servers, but I can't tell.
Anyway, it's probably not just you. The Global Shipping Program is being phased out and replaced with the confusingly-named "eBay International Shipping" service, which does and doesn't work the same way as the GSP. Start your search for info here:
https://www.ebay.com/sellercenter/shipping/ebay-international-shipping
Having said that, if the "system" has somehow figured out that you're in Canada, you may have been shut out of this new program. Right now, it looks as though your sales use the GSP for some items, and your own(?) shipping service for others.
