I remember helping someone who couldn’t access the wedding event while it was running, even though they had the correct update. It turns out, they weren’t able to trigger it because their time wasn’t synchronized with the internet (i.e. they were time travelling). Once they synchronized time, they were immediately able to do the wedding event!
I wonder whether Nintendo is treating the wedding event like a “special event” that can only be attended if you’re not time travelling? And if that’s the case, that would make the wedding inaccessible by default, since you cannot be synchronized with the internet and be in the wedding season...