I had to reset my indicator a couple years ago due to change in sprockets. Followed this procedure (copied from the gipro manual), worked a charm:
Reset the gear indicator:
5. Reset If some gears are not indicated correctly, reset the unit and set it up again.
- Have the engine stop switch in OFF position.
- Turn the ignition key ON and immediately turn it off while the GIpro display is counting up and is showing “3, 4 or 5”. Repeat this step 5 more times.
- On the next power up, the display will count backwards (“6 to 1”). The memory is now cleared and you can perform the Setup procedure.
Note: If you perform the Reset procedure, it will set the device to factory default condition. The Shift Light and High Speed Warning features will also be cleared.
Setup:
4. Setup You need to set up this module after installation. It is recommended to perform the setup procedure with WARM engine.
- Raise the rear wheel off the ground by using a stand . (If you do not have a stand, or your speedometer is driven off the front wheel, set up the unit while riding. Find a long, straight road with light traffic. The unit does not learn the same gear twice, this makes it ea sy to set up on the road. You can even shift down and stop during the setup if needed. Do not stare at the display, watch the road and ride with extreme care as always!)
- Turn the ignition On. The display counts backwards (“6 to 1”) indicating that the memory is clear. (If the display counts upwards when ignition is turned on, the memory is not clear. Perform the Reset procedure if you wish to set it up again.)
- The display flashes “L” (Learning) slowly. Start the engine in Neutral, and let it idle. The display flashes faster for a few seconds while the RPM signal is being received correctly.
- The display flashes “1” slowly. At this point, wait until the RPM drops to the normal idle speed. Select 1st gear, release the clutch and keep the engine at approx. 2 -4 times of your idle speed (usually 2000 -4000 RPM). The display flashes faster while the SPEED signal is being received correctly. The unit is now learning the gear position. Depending on the bike model, the learning may take from a few seconds up to a minute.
- The display shows “n” (next) for a second, then “2” flashes slowly. Select 2nd gear, release the clutch and raise RPM. Again, the display flashes faster while learning the gear position. Repeat this process until all gears have been programmed (5 or 6).
- In top gear, wait until “o” (over) is indicated and the display stops flashing. (If your bike has 6 gears, you will need to select 6th gear when prompted, otherwise the unit will exit from programming mode in 5 seconds and you will need to repeat the setup procedure.)
The unit is now programmed and should indicate all gears correctly. Now, when ignition is turned on, the display counts forward (“1 to 5” or “1 to 6”) indicating that it is programmed and fully functional.
The unit learns really quick, so you only need a couple of seconds in every gear.
But make sure you change up to 6th as soon as the display says so, or it will think you only have 5 gears and never show 6.
Maybe that's causing the problem?