I filed an AN3 report using Twinkle which was supposed to result in something like the section changed in http://en.wikipedia.org/w/index.php?title=Wikipedia:Administrators%27_noticeboard/Edit_warring&diff=621310927&oldid=621310299
Instead of that, it was submitted like the previous version shows, truncated in the middle of an external link. I confused the syntaxes for external links and internal links and used a pipe instead of a space to separe the URL and the label (I repeated that error in the edit supposed to fix the issue). I believe that error is what broke Twinkle.
This happened silently, I did not notice any error. I simply realized that a large part of my comments were missing, and congratulated myself for having copied the field's contents before submitting.
Note that I had to manually complete other fields after filing the report. Having the possibility to preview would have avoided and probably would have let me spot my syntax errors.
Once this is solved, http://en.wikipedia.org/w/index.php?title=Wikipedia:Administrators%27_noticeboard/Edit_warring/Header&diff=621574783&oldid=619382886 should be reverted.