Somehow the issue went away on its own
Anyway, regarding the initial issue, with 120 leds (per strip, so 240 leds total), when going into config mode, and choosing colors, it ends up freezing on the same color everytime.
Here are he traces:
START CONF
Main button longPress stop
Main button double click.
Main colorMain button click.
Main button click.
Main button click.
And then nothing responds anymore
I'm going to try and use the FastLED library instead of the library currently used.
FastLED library provided me good results when coding my PoCs, so maybe it will be better.