Am I just unlucky, or are the Amex platinum companion certificates basically useless?

I've had the Amex skymiles gold for a few years and been generally happy with it. When they raised the prices two years ago I decided to upgrade to the platinum since I was traveling with my partner more often.

After waiting out the first full year to get the first companion certificate (in and of itself annoying, but whatever), I've now tried to use the companion certificate for two trips and found that there is absolutely no companion certificate eligible flights on any travel dates that work for me. They all have plenty of main cabin seats, but not of the right fare class. One of them I can somewhat understand (it was a holiday weekend with less than a month's notice), although the plane was over half empty when I booked. But on this second trip, I'm attempting to book 4.5 months out and the plane is 80% empty - and still nothing! Only thing I can figure is that they expect Monday and Friday flights to be more desirable and thus make all or at least the vast majority of tickets on the flight a fare class not eligible.

I could understand if this were marketed as a "Great for the budget traveler with flexible dates" option, but that's absolutely not how it's marketed. And it feels especially bad given the annual fee is more than 3x the Alaska airlines card that gives a companion fare without the same restrictions!

At this point I've paid $700 for a companion certificate that I'm questioning if I'll even be able to use before it expires. At this point I'm probably going to downgrade to gold, if not cancel the card entirely out of frustration.

Am I just unlucky? Is it that using it out of SEA in particular is tricky?

Edit: thanks to everyone who weighed in and gave advice. I'll try calling and see if I have any better luck. The mix of "it's a you problem" and "oh yeah, mine always expire" comments are pretty comical - looks like how useful they are must be pretty location dependent.