It’s actually kind of hosed all around, it degraded to the point where it can’t use anything except the tazer attack.
The problem is several combined bugs, one is it always decides to use the grenade launcher, another is an error in calculating sight range, and the final one is the bug you point out that causes it to fail to use the grenade launcher unless it’s at exactly 38 tiles away from the target.
I almost have the bugfixes for all three wrapped up, at which point they will return to full lethality.