Solid State relay trips when load on Input change
You are probably getting switching spikes (transients) through your 5 volt or 12 volt adapter. Dimmers are often a source of spikes.

I would suggest trying, on the low voltage side of each adapter, adding a 0.1 uF disc capacitor in parallel with a 220 uF electrolytic capacitor. You can experiment a bit with the value of the electrolytic capacitor based on what you have available.