See PHI2029. An install reports that Jupyter notebook diffs render all inline comments on line 1 if the raw source file is a single line (for example, because the JSON has been minified).
This is //likely// caused by internal logic clamping the display line to the number of lines in the file.
---
When you are viewing a change under engine X, and comments made under engine Y are present, they are not handled specially.
- From T13534.