Nobody really knows what’s the proper way forward, since nobody at Fairphone has bothered to fill us in for quite some time… 
As far is I can tell, the issue has to be fixed by Fairphone, the Calyx devs have mentioned several times that it’s a bug in the bootloader. If that’s the case, that’s proprietary code and can’t be fixed by an outside dev.
There is a way to set get_unlock_ability back to 1 using Magisk, which you’ll find in this thread, but there is no guarantee that procedure reduces the likelihood of bricking the device.
I would #contactsupport , maybe this issue eventually gets prioritized at same point 