You can see the reasons for being late and leaving early on Attendance Reports.
Go to Reports>Attendance on the menu. Hover your mouse over the comment icon and see the reason. Note that you need to workspace members need to choose or write a reason on the pop-up so that you can see it.
Note that you need to activate these requirements in Settings>Tracker.
For the late-coming pop-up, turn on the Notify members when they are late from the scheduled time and check the Require to type the reason so they have to submit a reason.
For the early-leaving pop-up, turn on Notify members if they turned off the tracker earlier than the scheduled time and check Require to type the reason so they have to submit a reason.
