Apple Pay w/ watch says "see phone for instructions"

The last 5 or so times I've tried to use my Apple Watch to pay (over the last week or so) I have gotten the vibration that it went through but the reader has a message to see phone for instructions. My phone doesn't show any notification and I have just re-attempted the Apple Pay with the phone, and it goes through fine.

Any ideas? I'd love to be able to pay with the watch without having to pull out my phone.