Although it's a niche usage case, I thought I'd still post it here. With the January update, Frontier have split off the Guardian / Thargoid / Human / Other signals from the "Features" tab of the FSS interface, and they are now shown under a smaller "Locations" entry in the planet info part instead. So despite there only being a few out there in the deep galaxy, it's now easier than ever to miss them.
Have a picture, courtesy of freddyhard:
Although in the default colour scheme, at least the Locations part is in orange instead of white.
Have a picture, courtesy of freddyhard:
