User mentions only work for 24h after not invite

[hepcat72]

It took me a few days before I was sure that it wasn't something I was doing.

When I invite my bot to my server, user mentions work. I.e. mentions get highlighted and cause the iOS app badge to increment its unread count. But roughly 24h later, every message simply shows the mention as plain text and the unread count does not increment.

I can still mention @here and @everyone correctly, but user mentions just always eventually stop working.