When you view the Modified column in a SharePoint Online list, the list item shows the time stamp as "12:00 AM," even though no change was made at that specific time. The following conditions are also true in this situation:
Under Site Settings, Regional Settings, Locale, your locale is set as English (South Africa).
Under Site Settings, Regional Settings, Time Format, the time format is set as 12 Hour.
To work around this issue, set the time format to 24 Hour. To do this, follow these steps:
Browse to the site where the issue exists.
Click the gear icon to open the Settings menu, and then click Site settings.
In the Site Administration section of the Site Settings page, click Regional settings.
Change the Time Format setting to 24 Hour, and then click OK.
NOTE: After you make this configuration change, the time stamp will reflect an accurate time. However, it'll be displayed in 24-hour format.
This is a known issue in SharePoint Online.
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