LED strip lights not working properly on DC power
This is a typical SMPS common mode noise creating a differential noise voltage on the data.

These issues require an understanding of mutual coupling, cable shielding and ground network noise.  Many things can fix it.

I suggest you use your fingers to connect the DC 0V to some local earth grounds. If that works, then 1nF to 10nF  will replace your fingers and body.

Other solutions such as CM chokes with Pi filters to Earth ground  shielded cable for all noisy for LED and uC power and signals.