Tyre pressure light is on but tyres are fine?

So, my Ford Fiesta ST-Line 2016 has its tyre pressure light on and comes up with "Check Tyre Pressure" on the screen. I have checked all 4 tyres and they are fine. The car has been rarely used within the last 4 months due to injury but I'm concerned that there's something wrong.

Can anyone help?

These lights come on when the pressure drops below the manufacturers recommended setting. Make sure the tire pressures are correct. It only takes one being off.

Assuming you have checked the tire pressure with a gauge, and not just looked at them, and they are all correctly inflated, you either have a failed sensor or the system needs to be reset

Your tires (tyres) are "FINE" but are they inflated to the PROPER PRESSURE? Open the driver's door and look for the placard (sticker) that shows the proper tire size and inflation pressure for your car.

The TPMS is not too reliable. Mine worked fine for a couple of years, then for about 1.5 years I kept getting errors that showed the sensors were not transmitting to my receiver. Then for the last 1.5 years, all was working fine. They only measure tire pressure. They will not tell you if your tire is about to blow out. I really don't trust them to be reliable. Use a pressure gauge.

If you've checked the tyre pressure and it's OK ignore the light. Those sensors are not reliable.