I updated because another addon modified other addons and had an error or whatever, so the new version was 2.8 (last 2.7.1).
So anyway after re-adding 2.7.1 or just disabling the addon, the bug is gone.

The bug is that you can't Shift+select grouped items.
Which is super odd because this is supposed to be an importer, yet it's messing up controls elsewhere, so what's going on?

I'm using 2.78 64-bit windows (particularly a daily build but that doesn't matter because I tried it on the regular 2.78a build as well)