What distance checks you can use depends on the class you are playing. For 30 and 40 yard checks you need to have spells that cast on friendly targets with those ranges. If your class doesn't have spells like that Grid also can't detect if someone is within that range.
If you are a class with spells like that then I suppose it's a bug.
I noticed this with my Warlock. That makes sense about the distance options, I noticed when changing to another character than other options were available. I use 1 profile for all characters, so it confused me a bit. :) However, when using the Warlock units that are over yds away will not register as that. The only thing I see in common here is that the [Range] dogtag shows 28+ for units it works on and 30+ for units it does not work on. The units can be on the other side of EotS or AV, so they are way over 30 in all cases.