Can't change the due time

My default due time is 10:30pm, but when I change a item’s due time to another one, e.x. 2:30pm, it will reset to 10:30pm.
Is it a bug for OmniFocus Mac? I don’t have this problem in OmniFocus For iPhone.

What precisely are you typing into the Due field? “2:30pm”, or some other variant like “2.30 P”?

Can you please provide a screenshot of your date and time setup in System Preferences?

To find these settings, open System Preferences and choose Language & Region > Advanced…. Screenshots of all three tabs (General, Dates, and Times) would provide the most comprehensive information to help with this issue.

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