Inertia-reel seat-belts have saved lots of lives by ensuring that they’re always adjusted correctly on whoever is wearing them. They work by being able to mechanically detect sharp forces (such as would be expected in a crash) and locking instantly, limiting the movement of bodies in the process. In the meantime, they offer a huge degree of convenience by allowing you to move around in your seat without being squeezed by the belt.

But they can suffer problems with the inertia mechanism which can jam and lead to the problem you currently have. This is often because the car is parked on an angle, causing the mechanism to `think’ that the car has pitched violently and locking the belt as a precaution, even though it’s standing still. So test the seat-belt with the car sitting on flat ground. To be honest, inertia-reel belts are more likely to refuse to unravel to allow you to fasten them than they are to fail to wind-in or retract, so maybe there’s a small manufacturing flaw in the belt in question.

The good news is that your car is still under its factory warranty, so a trip to a Honda dealership should be able to sort the problem quickly and simply and at zero cost to you. The quickest, safest fix would be to simply replace the whole seat-belt unit and that’s probably what a dealer will do.