The error message should appear for the User field and unable to save with blank.
Record able to create with a 
This happens only for the Uncategorised option. Select that option and check.
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To reproduce, click Save and not Save & Close.
| Status | New | ⇒ | Closed |
| Closed_Date | 0000-00-00 00:00:00 | ⇒ | 2020-01-10 17:10:47 |
| Closed_By | ⇒ | Quy |
I could not replicate this