cannot access target shutting debug session when run stop mode with RTC in examples
Yeah, debugging the chip is real difficult when the power is removed from all the scan chains and logic you're communicating with....
Check DBGMCU settings for options.
Consider using USART or other methods to output diagnostic and debug info when the device powers down, and up again.
Debug as much of the code as possible without actually powering down.
Understand your code flow without needing to see every step.
Retrieving data ...