Picto not working very well

Hi everyone. I am developing a module, and the picto value doesn’t seem to work very well to me.

If I use a value of “building”, the icon appears just fine on the Module setup page, and on the index page of my module, but the icon does not appear in the top menu bar.

If I use “car”, nothing appears at all. “car” is a valid picto reference.

Anyone else having this issue?