Capacitive touch insulation problem?
Your symptoms are not surprising at all.  From the schematic, we know that the capacitive sense method is effectively measuring the change in capacitance to ground, not some other specific conductor for the purpose.

The real problem here is that you are just sticking blocks together without understanding how they work.  You need to actually stop and understand capacitive touch sensors and what "PWM" means and the implications thereof.  Blindly connecting subsystems at this level will get you into trouble, as this example shows.

The LED strip adds significant capacitance to ground, and even worse, adds significant noise due to the PWM drive.  Basically, your capacitive sensor isn't going to work with the LED strip near it.

"Insulating" the LED strip from the sensor makes no sense either.  Capacitors are already insulated between their plates.  Shielding the sensor from the LED strip might help in that it will reduce the noise from the PWM.  However, it will also add significant capacitance to ground so that the change in capacitance due to a touch is a smaller fraction of the whole.  These signals are already small and noisy, so a shield may also keep the sensor from working.

A shield at a far enough distance would help, but ultimately using the wrong building blocks for the situation is not a good strategy.  There are other types of capacitive sensing that are more appropriate, but that doesn't work if you're just blindly "playing with the capacitive touch libs".