I have to say this is a RECENT problem: I have been sending stuff to Canada since the 1990s when I started doing this stuff again. It's only been since last year that (most of) these packages have gone missing. And, knowing what happened to me here in the States after the 9/11 attack (i.e., anything with wires got opened, inspected, sometimes returned or simply "lost" in shipping), and knowing Canada has had some recent terror attacks (bombings, shootings), has me thinking it is the same problem, but in a different Post Office. I don't understand how this could lose 2 envelopes with O-rings in them, however...but for the other items, all of which have a bunch of wires in them, I am suspecting it is a 'lack of expertise' issue within either Customs, or Canada Post, that is preventing them from getting to their destination.
Maybe if they get better at it, or if someone stops the attacks there, the problem would go away? Just musing...the fact that the Tracking simply stops at the border seems to point to Customs, for now. But, the USPS also deletes the Tracking to Canada after about 30 days (while they keep the ones within the US for over a year, I have recently discovered), making further investigation almost impossible, now. Grr...