SMS messages say "Message Send Failure" but go through?

Whenever I receive a notification for an iMessage on my Apple Watch 4, I'm able to respond to it and it works great.

• Whenever I receive a notification for an SMS message, I can respond to it, but a few minutes later I get a notification on my watch that says "Message Send Failure", indicated that the message failed to send.
• However if I open Messages on my iPhone it shows that the SMS did get sent and the other person did in fact get it.
• So it seems the messages are sending properly, but every time I get a notification on my watch saying the message failed. It's really annoying constantly getting this popup even though the message was successful.

This happens whether or not the watch and phone are connected with Bluetooth.

Things I've tried already:

• Disabling and re-enabling iMessages and SMS messages on phone and watch
• Rebooting phone and watch
• Turning off and on again Bluetooth and making sure watch is connected to phone via bluetooth