Yea, it's difficult to convince a decent AI to get installed in one of those things. Various complaints of "made of tissue paper", "has all the range of a sharp stick", etc. So they tend to get the, um, "less observant" AI modules. Perhaps some of the ones from Bionic.
Anyway, is all the mystery solved or what? If you give them a direct attack order, they teleport over and then shoot at other things... for any discernible reason? Are they getting displaced too far away to shoot at it?