Thanks for your suggestions.
It seems that both tuners are used simutaneously during scan. I’ve also tried to disable one or the other, but no change.
I’ve also tried another stick, a Pinnacle 72e, with the same Dibcom7000 chip but only 1 tuner, and scan fails the same way.
I’ve finally had the idea to test a NooElec Nano stick, without changing anything else, and this time scan works! But it isn’t a solution for me because i use this stick for another purpose.
So it doesn’t seem to be related to muxes settings, since it worked well with pre-defined ones.
I’ve then retried the other sticks, keeping the discovered services, but they both failed to receive any channel.
Since i have the same problem with 2 different Dibcom7000 sticks, i wonder if it could be related to this specific chip. I’ve checked linuxtv firmwares, but the latest “dvb-usb-dib0700.1.20.fw” firware seems to be the one already used:
osmc kernel: dvb-usb: downloading firmware from file ‘dvb-usb-dib0700-1.20.fw’
And i’ve also tried the same sticks with an old Synology NAS: it works OK and seems to use the same ‘dvb-usb-dib0700-1.20.fw’ firmware. So it seems that firware is OK (except if the one coming with OSMC is corrupted, is that possible?).
So i still stuck with 2 DiBcom7000 sticks not working only with OSMC/TVHeadEnd, but working anywhere else… And the same OSMC/TVHeadEnd install working with a NooElec stick.