Using attach creates View Attachment X link

[Foxtrek_64]

As it says on the tin. If I use the [attach]12345[/attach] bbcode, with or without the =full argument, I get an anchor that says "View attachment 12345"

Clicking the link will open the attachment in a new tab, but I can't get it to actually display inline.
How can I get the image to display inline? Is this a cache issue perhaps? It does not appear to be related to what theme I have selected.
Using attach creates View Attachment X link

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