Chromebooks need to be set to always stay on
Set the Chromebook to never sleep. When chromebooks are permitted to go to sleep after a period of inactivity they need to sync with current time upon use. This could take even a brief period of time for it to do so resulting in the potential of someone clocking in/out prior to the completion of that sync process and the time collection for that user may then be inaccurate.
This is for an unmanaged chromebook, but if the device is registered to an organization then change the sleep settings through the admin console.
https://support.google.com/chrome/a/answer/2657289#zippy=%2Cidle-settings