iMessage badge always shows one unread message

iPod Touch 6th Gen, iOS 11.4.1

My iMessage always shows there is one unread message, even when all existing message threads are deleted. It also doesn't update. I could have 417 unread messages, and it would still say 1.

I did a power button-home button reset, as well as a power-cycling and neither worked. I also disabled iMessage and reactivated it, disabled and reenabled both all notifications and just the badge.

It had been fine since the update dropped (last version had no iMessage badges appearing, and the version before that had this same issue), but the speaker suddenly disabled itself, so I did a power-home reboot and then I got a spontaneous badge even though the last message I got was just before the power-home reboot, and it's been there ever since.

Any ideas?

Also, any ideas why each update seems to bring with it some sort of iMessage bug?