"Item Status: Automatic cleanup was not successful, manual cleanup is required"

According to the built in Help, you supposed to ...

Add a custom scan of a threat

If a threat is listed in Quarantine Manager, you can add a custom scan of that threat.

1. If the Scans window is not open, choose Window > Scans to open it.
2. If the Custom Scans list is not displayed, click the disclosure triangle next to Custom Scans.
3. If the Quarantine Manager window is not open, choose Window > Quarantine Manager to open it.
4. In Quarantine Manager, do one of the following:
   • In the list of threats, select the threats that you want to add to a new custom scan.
     Drag the selected threats to a blank space in the Custom Scans list.
   • In the Threat Details box, select the files that you want to add to a new custom scan.
     Drag the selected files to a blank space in the Custom Scans list.
   • In the Threat Details box, click Path and Filename, and then choose “Create a Custom Scan of These Files” from the pop-up menu.
5. In the scan editor that is displayed, to rename the scan, in the Scan Name field, type the new name.
6. In the Options pane, choose “Delete threat” from the “When a threat is found” pop-up menu.

The scan is added to the Custom Scans list.

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The problem I found was that you cannot drag the threat or the files into the Custom Scans window as it describes.

They just won't drag and drop.

Sophos 9.5.2

I concur.

I concur.