My single.php page skips the first div tag

While it is not officially answered the question, it is a suggested debugging technique for future audience to see how to resolve the related problem:

If you ever meet such situation. Then most likely there is some tag(s) is(are) missing creating such cascading effect. So

  • could try to hide the content output first to see if it is the html inside the content creating issues.
  • output the code piece by piece by replacing content with static content, and then add part by part to find out which produces missing tag(s) effect

After spotting out which part(s) could reduce time and effort to pinpoint the problem.