Cron job missing after power failure

[brighteye]

NOTE:
After a crone job is properly saved and there is a power failure the cronjob will not be available afterwards.

STEPS TO REPRODUCE
01. Launch crontab crontab -e
02. add a line at the bottom i.e. #power failure test 1
03. save file and exit
04. sudo reboot and wait for until booted up
05. again launch crontab -e
06. observe that last line includes #power failure test 1
07. add another line at the bottom i.e. #power failure test 2
08. save file and exit
09. unplug raspberry pi from usb c power
10. plug in raspberry pi power and boot up
11. again launch crontab -e
12. observe last line of file

Expected:
#power failure test 2

Current:
#power failure test 1