I have 3 light installations in my kitchen that are controlled by one of two switches. The switches either turn all 3 lights on/off, or dims/brightens all 3 lights at the same time (with a long press).
Lights cannot be turned off individually, or dimmed individually, only from these two switches.
However! Today, something changed: when dimming the lights, 2 of the lights dim (correctly), but the other light brightens. When brightening the lights, only 2 brighten, but the other dims: the relationship appears to be inverted.
This change happened spontaneously: I didn't do any re-wiring, change any bulbs, etc.
This behaviour is exhibited when using either of the two switches.
The below picture is of the dimmer: the top switch is the problematic one. The bottom switch controls a different light, which is working properly.
How should I try and debug this issue?