Migrating Sandbox -> Cloud Join Issues

Hello,

I’m migrating our fleet from the Sandbox version of TTN into the Cloud Discovery version and following this guide: Between The Things Stack distributions | The Things Stack for LoRaWAN .
I’ve moved three of my devices over (waiting to move Gateways at a later date), and i’m getting join requests successfully to my devices on the Cloud version (screenshot attached). However, the devices don’t ever seem to receive any data. The uplinks are still happening on their regular cadence, but they’re just the join attempts.

Any thoughts on what’s going on here?