Some have thought the Canada Post on-again, off-again dispute this summer was the initial and continuing cause of lower sales. Some theorized the change to $CDN-only on .ca was the culprit.
Like you, I've been in a real slump. The period of mid-September through mid-November has for years -- actually as long as I've been selling on eBay -- been my best. Not in 2016 though.
Personally I can't believe either of the above theories is the real cause. I have a different hypothesis. I think there is something external to eBay and to Canada itself that is at play. The reason I say this is that:
a) I usually sell primarily to Americans, more than 90%. The remaining 5%-10% is about evenly distributed between Canadian and overseas sales. Ever since July, things have not been good. I can't see the Canada Post tiff having such a longstanding effect on U.S. sales right into November, especially since Americans were probably not aware of it in the first place.
So what happened in July? What happened in November? One word: Trump. My guess is that a deep angst amongst Americans about the future is the cause for a reduction in discretionary spending on "luxuries".
b) Popular items of mine that have always (i.e. before July of this year) flown off eBay almost as soon as I've listed them, nearly always purchased by U.S. buyers, are now still sitting nearly 2 months after being listed. This for me is unprecedented. Nothing else that I can think of has changed in terms of my eBay store (I've been listing in $USD on .com for over a year now). The only change I can think of that would cause such a significant slump in the purchase of my products is the political situation in the U.S.
c) Oddly though, those popular items are still getting the hits and watchers I would normally expect. They're just not going to the next step to buy.
d) On the other site on which I sell, there has been a comparable drop-off over the same period (there, my sales are about 75% US, 25% overseas and Canadian). Prior to July, and for the previous years, things were doing terrifically there. Not anymore. In fact, for the sales that did occur during that time period, Canadian and overseas buyers have outnumbered U.S. buyers.
e) On my other site, shipping is not involved. So Canada Post cannot have had any effect there. Yet sales have taken a dive.
f) My website hasn't suffered at all with respect to number of visitors, in fact it's grown more than usual. Still, despite all the connections to eBay and elsewhere where I sell, conversion has dropped off the map.
So in some ways, although I'm a small, "boutique" seller, I may be the ideal guinea pig as a test of the Trump theory: I've been listing on .com in $USD only, I have unique products that have historically been very popular with U.S. buyers, and am seeing the same low sales levels on the other site on which I sell, even where shipping isn't involved.
I can't think of anything else that has occurred over the summer and autumn to explain it. I can't even blame the "cart disconnect" on eBay, which although now fixed, didn't affect me at all once I moved over to .com a year ago.
Increased competition might be a partial explanation, but not in my category or my particular products (I have only a handful of competitors, but in slightly different areas). And eBay's online competitors have not all suddenly appeared at once over the past 4 months.
What else is there? I'm just waiting it out, like everybody else.
