B737-800 First Officer reported the trailing edge flap indicator had a split between left and right flap.

Narrative

Upon leveling off at our cruise altitude; the Captain and I noticed the trailing edge flap indicator had a split between left and right flap. One was indicating fully up while the other was beyond that showing that it was even 'more up' than the limit. Upon further discussion we agreed that it was probably an indication issue as it's impossible for the flaps to be split in that manner. We decided to extend the flaps early on descent in case of any issues with deployment. At around 10;000 MSL I called 'flaps 1'. The Captain moved the flap/slat handle to the 1 position. There was no indication of motion of flaps or LED's. I remained the flying Pilot and took over the radios after we requested priority and requested a Runway (XXC) from Regional Approach at ZZZ. The Captain and I had a brief discussion on which checklist to use. We agreed on flap asymmetry since that was what the indicator was depicting. We were able to get the LED's extended fully and land via the trailing edge flaps up checklist. Upon landing we taxied to the gate normally with Airport Rescue and Fire Fighting following. Worth note is that after landing the trailing edge flap indicator reverted back to normal.I'm not sure what caused the trailing edge flaps to not extend.