I made a stop with the name "(icon of legendary rocket fuel)Truck Dropoff" to let my trucks know to drop legendary rocket fuel in that stop. When viewed in alt mode, the stop's name is shown as "[item=rocket-fuel,quality=legendary]"Truck Dropoff" in full text, instead of showing the rocket fuel icon.

Thanks for reporting it! The stop's name label (alt mode, and on the map) was drawn as plain text, so icons showed as their code. Fixed in the next Autopilot update: icons in stop names show as icons, and existing stops get it when the game loads.