DDJ-RB, problem with buttons

I have a Pioneer DDJ-RB, and for the past few days, the left-side 'Play', 'Cue', and 'Sync' buttons haven't been responding.

Even though they light up normally and seem to have power, pressing them doesn't seem to send any commands. I am currently forced to use these buttons directly from my laptop (via the software).

Two electronics technicians have looked at it (though they aren't specialized in DJ controllers), and they told me they couldn't find any issues, claiming that whatever the right side gets, the left side gets as well.

Any thoughts on what might be wrong or what I should check next?