If:
-
Safe mode doesn’t change anything
-
You don’t see anything related in
admin/logs/staff_action_logs -
You don’t see anything related in non-default setting values
-
You don’t see anything in
logs/ -
There’s no clue in JS console or in the network tabs of your browser’s dev tools
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Don’t see anything in the HTML code (in case some CSS or browser extension would hide the field)
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Updating Discourse (ideally, rebuilding from the command line) doesn’t fix it
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If you don’t have any recent backup in which the field was visible
You can continue to search and wait for help, or maybe save some time and sweat by reinstalling Discourse. It’s not necessarily an overkill solution, especially if your installation is fresh.
But it’s also frustrating not understanding why this issue happens.
That said, to me, it looks like either a setting quirk, or a bug. 