It's only designed to work with fully opaque rs3 interface mode. It might also fail if some other interface like the clock is on top of the minimap.
Sometimes when using Alt1 for an elite scan clue it works perfectly and shows the range but other times it will give me "Show range - failed". I don't think it's about which place the scan clue is for because @times I've saved clues for later and gone back the next day and it's worked fine. Any suggestions?