Apple Watch 10 connects to treadmill but doesn't record activity

Up until yesterday, I have had no issues with connecting my watch to the treadmills at my gym. However, yesterday, I connected my watch as normal, selected indoor run, but then it just went back to the main workout menu. The treadmill showed the little connected symbol on the screen, but the calories and heart rate which normally then show on the treadmill weren't there. I ended up having to selecting indoor run again but it didn't reflect the treadmill. Does anyone know why this is? I've had my watch for about a month and haven't had any problems up until now. My friend who is there at the same time connects hers without a problem and I have tried it on numerous machines, so it is definitely the watch! I have toggled "Detect Gym Equipment" off and on and this hasn't solved the problem. I have also rebooted my watch.... please help!