‘Forbidden’ error when saving existing snippet

I’m able to create new snippets, and can change their active status from the Code Snippets listing screen. However, any attempt to save edits to an existing snippet returns a blank page displaying a ‘forbidden’ error.

This occurs for all admin users of the site.

What I’ve tried so far:

• Checked for blocks in WordFence. (No log entries corresponding to the save attempts, no relevan blocks that I could see.)
• Confirmed not in ‘Simple’ mode. [https://wpcode.com/docs/how-to-fix-wpcode-permissions-error/]
• Updated WPCode plugin.
• Deactivated/reactivated WPCode plugin. [https://wpcode.com/docs/how-to-fix-wpcode-permissions-error/]
• Removed/added admin role to my user. [https://wpcode.com/docs/how-to-fix-wpcode-permissions-error/]

The one relevant tip I found at the WPCode site [https://wpcode.com/docs/how-to-fix-wpcode-permissions-error/] suggests this is usually a permissions error – can anyone point to where the permissions are documented, so I can try to manually update in the database?

At this time I’m not able to reproduce the behavior on our staging site. (Possibly relevant: Plugin had been removed at some point on that site – no record of that so not sure when or why – so when it was installed/activated on staging, it was a fully new download, not just deactivate/reactivate. Old snippets were still in the database from the previous install, though, so it wasn’t a complete blank slate. Could deactivating & then deleting the source module potentially cause the permissions to get reset when it’s reinstalled/activated, even if they didn’t get reset by the deactivate/activate process?)

Does anyone have any comments on what I’ve done so far, or other troubleshooting suggestions?