RTCZero sleep mode and wake it up after one minute SamD21

Hello!! I am carrying out a project with the RTCZero library in order to put the SamD21 microcontroller in sleep mode for 1 minute and then wake it up to send data from some sensors, then put it back in sleep mode and repeat the cycle. The problem I have with the program is that after a certain time (6 or 7 hours) the microcontroller stops sending the data (measured by sensors) so I think the RTC Zero fails. I would be very grateful if someone gives me a solution. Thanks