Sometimes diff isn't shown in edits to code inside source fences

Question

It seems the visual highlight of revision/code differences in source fences is currently broken for some posts in the suggested edits review queue.

• Example 1. In this post. The 3rd line of code was edited but there's no visual highlight.

  

• Example 2. In this post. The code line was changed but there's no highlight, notably the source fence is one single line.

  

• Example 3.1. In this post. There seem to be two inconsistencies, the difference highlight is shown when reviewing the item in the review queue.

  

• Example 3.2. but if you review the edit by clicking the edit link directly on the post the diff highlight is not shown.

  

I think the highlight difference is essential for reviewers, I was left starring at the source fences trying to find the differences in code when reviewing these items.

Answer 1

The hotfix from my answer on Meta Stack Overflow has been expanded to cover the /review/suggested-edits/{id} page. Highlight.js was overriding the styles used for showing additions and deletions. My hotfix turns off Highlight.js on these revision pages so that additions and deletions are shown correctly.

Notably, the hotfix has a regression of turning off syntax highlighting on this page. See my Meta SO answer for more details.