OmniDuck

It doesn't really affect anything, as the Northern Mines is a dead end, but I'm a completionist and that lonely red border is irritating. The official guide suggests that all four mine areas are cleared by walking from East to West and turning off the defences in the Mine Core. But I've done this, and while those three areas are cleared, the Northern Mine isn't [although I think I've done everything that I can there]. I know one of Jeff's version updates [maybe 1.0.2] said that 'Northern mines can now be cleared', but I'm running v 1.2 taken from disc only a couple of weeks ago.