Same issue faced, Then tried an alternative method to read serial number using shell command. But same result empty for serial number. Fetching all other details of monitor but empty for ""spdisplays_display-serial-number"" key.

Our application trying to run an script file, which is located at /Library/Scripts folder. sample : 50 15 27 05 * /Library/Scripts/scheduler_run General crontab method like, "crontab -l" is also not working when sandbox enabled. In this application cronjob need to run for all users.