Solved! Go to Solution.
With the phone powered off, press + hold the volume up and power buttons until the Samsung logo disappears. Using the volume keys, highlight wipe partition cache and use the power button to select and confirm. Reboot the phone from the menu with power key. See if this fixes it.
If the problem persists, could you tell me your baseband version?
Baseband version N986USQS5HWG8
Edit: kept trying to run it and I guess for some reason it fixed itself-solved for me at least