DDJ-800 Loop & Quantize button not working

Dear community,

I have an urgent problem with my DDJ-800.

On my left deck, the loop in/loop out as well as the quantize button are not working anymore. On my right deck it's working as expected. 

It all worked fine until two days ago. 

DDJ-800 firmware is 1.02, driver 4.0.1, and rekordbox is 6.8.5 (I also tried it with rekordbox 7, same result)

I also tried restarting, unplugging.

I found the same issue with other users in the web but there never a solution to the problem. 

Please help, I have my next gig in 4 days!

Best, Arthur