First off, check the suggested edit itself. If there is also an Edit action by another user on the suggestion, then a user with 2,000 reputation clicked the Improve button on the suggestion and unticked the "this edit was helpful" checkbox, meaning he/she did not think the suggestion was good.
However that's not the case here, as no such user appears in the revisions history of the post. (Fabian edited it now, not related to the suggestion at hand)
This means five minutes grace period case: if the OP of the post edits within five minutes, it's not logged anywhere - the last edit he/she made will appear as the initial post.
What happened is the following:
- OP posted original question.
- Less than one minute after that, he clicks the edit link.
- One minute later you suggested your edit.
- OP confirms his edit thus "kicking" your suggestion away - as part of the approve/reject/improve mechanism, when edit is made by other user it means "improve" which used to be just "approve and edit yourself" but recently we gained the ability to "reject and edit yourself" so I guess it became the default behavior.
Bug or by design? Not for me to decide. :)
Note: once edit was suggested, the post can't be edited (no "edit" link) so it means step 2 must come before step 3.