Got a weird problem...

I've recently changed from:-

Generation 1 EvoHome + WiFi Bridge + 2 x BDR (Y Plan)


WiFi Evohome + Opentherm Bridge + Single BDR (Hot Water Only Valve)

Everything is working perfectly. No comms errors, hot water valve opening and closing as it should. Yet despite this, the red light is illuminated on the BDR. I've done the full reset (long press) and re-bound it a couple of times. Still the light is red.

Any thoughts?