With some topics it appears as though the question mark subject icon is corrupt. I put it for this topic to double check.
EDIT* It seems to work here, not sure why it doesn't over there
(https://i.imgur.com/Xy3k4ws.png)
If you are talking about the icon on Jarky's and your topics, and those not showing up, I would guess, if it works here, I'd assume it's how your browser handles them.
They look different from the question icons I see when I'm on this site, so that is what draws me to that conclusion.