As of today comments do not render MathJax and remaining text. It only flashes the underlying LaTeX, but renders an empty space. Noticed on MSE and MO, for example here one comment now simply reads: "@Eric Write – Aweygan Jan 26 at 14:08 ".
Have tried different MathJax renderers or other MathJax context menu settings.
The problem appears on Windows 7 32bit and Firefox ESR (with a clean profile too). Works normal on Chrome and the new Firefox Quantum.
UPDATE: Broken on Tor Browser 7.0.2 (based on Firefox 52.2.0). But works on PaleMoon 27.7.1! Broken on Basilisk web browser.