I've found the same problem; since updating the os to v.2 it only seems to happen when the arp is running with LFO saw wave doubling the beat (i.e. LFO syned to arp, arp rate ~ 9-10 o'clock, LFO rate at ~ 2-4 oc'clock.
An audible click occurs apparently at random, certainly not in time with the cycling arp. I've used an isolated power supply to exclude other possible surge sources (shower, fridge etc). It might run for fifteen seconds, or a minute, or two minutes, then just when I think I've got a clean take - 'click!'
Any advice, Bruno?
Apart from this little glitch, it's an amazing machine