Garmin speed sensor 2 0kmph reading

I run the garmin speed and cadence 2 sensors connected to my ipad on a classic trainer and it’s been working perfectly for a couple of weeks until suddenly yesterday the speed sensor started reading 0kmph. I had just stared a race, i had done the warm up and as my Bluetooth headphones were playing up, I stupidly turned off the Bluetooth on the ipad and the ride froze (yes, im an idiot). Since then it’s impossible to get a reading for speed on the ipad. On my garmin 510 the speed and cadence both read correctly, ive changed the battery on the sensor, relinked it to garmin connect, checked that i had the updated software on both the sensor and the ipad, deleted the app from the ipad and reinstalled it and also downloaded Zwift onto my phone, which had the same result. Curiously, ive also put Zwift onto my wife’s apple laptop and it works fine, both speed and cadence read correctly. At the point when i open the app on the ipad the sensors normally connect automatically, it initially says that the speed sensor is connected but reads 0kmph and the cadence sensor is aso connected and shows the rpm. Then after a minute or so the app tells me the speed sensor has no signal. If i open a ride the avatar obviously doesn’t move but an rpm does appear. Please please please help!!! I’m about to throw the bike, ipad, trainer and sensors all out the window in frustration.