Hi,
Does this issue continue if we try using Outlook within safe mode? To open Outlook in safe mode, press Windows key + R to open the Run command, type
outlook /safe and press Enter.
In addition, are you using a custom task form and setting it as the default task form? To verify this, go to Tasks navigation pane, right click Tasks folder, select Properties. Make sure "IPM.Task" is selected for "When posting to this folder,
use:".

Regards,
Steve Fan
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