The BT classic mode in the new app still relies on BLE to provide an initial connection (it’s complicated - but we’re going to make it a pure BT classic connection at some point, at which point it’s more likely to work for you - why I said it might work).
I’ll be honest, for the new watches (which don’t support BT classic) it would take some re-architecting how BLE works with Pebbles to make it work reliably with multiple pairings, and we just haven’t had enough people ask us about that for it to make sense putting in that effort.