I am able to add a new value to a time field successfully. But when I am trying to update the same row, the update is happening in the backend, but not reflected in the UI.
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Please take a look at this thread, as it appears to describe a similar issue to the one you're experiencing.
https://community.appian.com/discussions/f/user-interface/18504/datetime-field-issue-updated-value-is-not-displaying