Seemingly at random, I can't propose edits for some questions.
An example is Third party shore-excursion operators in the Western Caribbean. I can just see
link - close - flag below the question.
But I can edit US Customs Pre-clearance in foreign airports, even before it got an answer. I see
link - edit - retag - close - flag on that question.
It appears to have nothing to do with my score in various tags, unless I'm missing something.
It looks like I can propose an edit if I go directly to the edit page -- e.g.
https://travel.stackexchange.com/posts/426/edit for the first question.