Blue 2-1 switch causes light to flicker and hum ONLY when remotely turned on

Hi all! I’m having an issue with a new Blue 2-1 switch that I have installed to replace a Lutron dimmer switch. When I turn the switch on at any power level locally at the switch I have no issues. When I turn the switch on remotely (i.e. with Home Assistant, Zigbee2MQTT, etc) at a power level over ~15% the light will flicker and produce a loud humming / buzzing noise. It only happens when remotely controlled. I’ve turned the switch on and off 100+ times to try to reproduce it and can’t make it happen when using the switch directly/locally.

Setup info:

The Blue switch is setup in as a single-pole dimmer. Replacing a single-pole dimmer.

I’ve tried a Red Dimmer switch in the same spot and it does NOT do the flicker/hum when either locally or remotely controlled.

The outgoing switch was a Lutron MA-600. This appears to be an MLV-compatible leading edge dimmer, same as the Blue switch.

The fixture is an Elco Lighting EL1499ICA 12v transformer which supports MLV-compatible dimmers, per the spec sheet.

The bulb is a single GE EXN 12v 50W MR16 halogen bulb. I have more of these bulbs hooked up to Red Dimmer switches (with no issues) but this is the only one that I have hooked up to a Blue switch. I’ve tried 3 other models of halogen bulbs and 4 models of LED bulbs (8 bulbs total) all with the same result.

I’ve tried tweaking min/max levels and ramp time with no change to the issue.

Any advice on what might be causing this flicker and hum when I control the dimmer remotely?

An update: I updated the firmware of the Blue switch from 2.00 to 2.05 and that seems to have fixed the issue. I’ll report back if it happens again but if anyone else is having this issue I’d suggest trying to update the firmware on your switch.


Sweet! Mark post as resolved if you feel it isn’t an issue anymore so we know!