"Sim Empty" and cannot make calls after upgrade

I have a WileyFox Swift which I recently updated to Nougat. Wileyfox runs Cyanogen natively. I have not rooted it or hacked it in any way. I installed the update by clicking on a reminder that kept popping up telling me to update. So everything has been done in the official manufacturer-defined way. It has two sims. When I reboot it asks for the sim lock PIN for one of the sims (the other does not have one) so I know it is detecting the hardware. Also I am able to receive SMS on one of the sims. But I cannot make calls, receive calls, or send SMS. When I go to "Settings -> SIM cards" it says both sims are empty.When I try to make a call, instead of giving me the choice of sim, it only offers emergency call. I have tried rebooting, re-seating the sims, going into recovery mode and clearing the cache partition.