Hello good..
I have had this error on 2 sensors in a row, with the previous one I tried to activate it 3 times and after waiting the corresponding 3 hours I changed it.And after waiting 1 hour this one came back to me.The application comes up again to start it and counts the 60 minutes again.

Thank you and I'm sorry for the inconvenience.
Edit: The third one I have used does not have NFC working (I have tried several old ones in case it was the phone and it detects them without problem).Let's go for 4th, today I'm not even asking for them to score well, I'll settle for them to start.😓