Flights Climbed data in health has stopped working

Currently training for an uphill half marathon. Until the 2nd of Nov the "flights climbed" part of Apple Health was calculating the altitude I'd achieved. From the 2nd of November it barely registers. I don't want to manually input the data daily, nor do I want to download another app. I'd just like it to restart its stats correctly. There's been no damage to the phone and all other parts of the Health app are working fine.