In a recent comment, one occurrence of stars-to-italics ('particular') doesn't render, but one does ('abstract').
This seems to be a bug. Is this the right place to report it?
EDIT: Now also posted on Meta.SE.
EDIT: Per @MartinSleziak's investigations below, it seems to be something about a MathJax + Markdown combination like "$\cong$—spacer italics spacer—$\mapsto$" (
$\cong$—spacer *italics* spacer—$\mapsto$) (as comment). It renders properly in the body of the post, so perhaps it's just a comment thing (as MartinSleziak helpfully indicated in the tags!).