I have a similar issue. It used to work but no longer does. Works in my friend's s8. I've tried disabling/clearing data and reinstalling for all the vr and oculus apps. I've tried a factory reset. Still doesn't do anything. Reinstalled all the apps again. Still nothing. My phone usb-c still works so I don't think it's the connection either. Rebooted lots. Tried an older version of the oculus app. I also disabled app power monitor, still nothing. It can recognize the controller but not the headset. I've found a lot of threads online with similar issues but no solution so far.
I haven't been able to fix this. I contacted oculus support who responded that because my S8 is unlocked (not locked to a cell carrier) it is not supported by gear VR and they can't guarantee that it would work. The fact that Gear VR does not support unlocked S8 phones would explain why so many people seem to be experiencing this problem. Unfortunately with no support the only hope for the Gear VR to function again is if a future android update happens to be compatible with the software. It would be nice if they either chose to support unlocked S8s or actually disclosed that unlocked S8s were not compatible rather than marketing it as a product for the S8.