V6 and RF60 sporadically does not fire
I have a new V6 with two RF60 flashes used with my Pentax K-3 DSLR. On a recent outdoor photoshoot all worked well with the two RF60s in slave mode and in two groups, but after some 30 flashes the radio triggger to one of them stopped working and after yet a handful of flashes the other RF60 stopped firing. Manually both flashes could be fired (by pressing test button on flash). Both flashes and the V6 had new batteries. When I got back home I tested the setup and then it worked fine. My initial thought was that maybe the decreasing outdoor temperature (getting down to 0 deg C during the shoot) had made the wireless circuit go down (even if it is specified to -20 deg C), but a similar issue just happened on an indoor shoot. Now one of the flashes (same setup; slave mode in two different groups) did not get the radio trigger and only after several power cycles of the RF60 it did start to work as expected. In both of these cases the distance between V6 and RF60s has been 3-10 m and without any odd wireless environment.
Any help on the issue is much appreciated. Not even sure if the problem lies in the V6 or the RF60s.