Let's start by checking the bell crank to see if it's adjusted correctly. This is just a visual inspection and shouldn't take long at all. The bell crank connects the shifter cable to the Shimano Nexus 3 Internally geared hub and is located just in front of the basket on the Compass or the center of the rear wheel on the Dash. You can see it highlighted below.
Please ride the bike with the motor turned off. Shift into second gear as marked on the shifter, and let the bike coast for at least five seconds.
When the shifting is adjusted correctly, the yellow indicator on the movable arm inside the bell crank should line up evenly between the two yellow lines on the sight window, as shown below.
If your indicator is not lined up correctly, the adjustment takes just a moment and the only tool you should need is a 10 mm wrench.
The first step is to check is that the bell crank is installed fully on the axle. Remove the bell crank from the axle and reseat it to be sure that it is on all the way. Simply loosen the fixing screw and pull the bell crank directly away from the bike to remove it. Press it on firmly, then tighten the screw. It may not sit flush agains the bike's frame and that is perfectly fine. It is located off of the axle, rather than the frame.
At this point, please re-check the alignment of the indicator between the yellow lines. If you do need to make an adjustment, you must loosen the locknut on the cable's barrel adjuster, shown below.
Turning the barrel adjuster out (counter-clockwise as viewed from the front of the bike) to move the indicator closer to the frame. Turning it in will move the indicator farther away from the frame.
Turn the barrel adjuster until the indicator lines up evenly between the two yellow lines on the bell crank's sight window.
If you prefer a video, you can see this process here: https://www.youtube.com/watch?v=H-UKc42fZx8
Go for a ride and check the shifting!
If it's still misbehaving a bit, I've seen a few where even when the indicators line up nicely they need a little further adjustment. Go ahead and back the barrel adjuster out another half turn and try again, then another half turn if that doesn't get it. If it is still misbehaving, please put the shifter and hub into 2nd gear then send us a photo of the alignment of the 3 marks on the bell crank.