All of my unmanned probes have vanished from the tracking station. I can't see them, I can't control them. When I launch a new one, it doesn't have an icon in it's own map screen and as soon as I return to the space center it vanishes. I've managed to find the vessels in the save game file, so it appears they're still out there, but I have no idea how to make them trackable again.
I've been playing KSP vanilla for some time but I recently installed mechjeb and mechjeb integrated, because I was tired of docking and performing holtzman transfers on my own. It worked fine for several days so I'm not convinced that the mods have anything to do with my issue. I haven't tried removing the mods yet, I suppose I'll try that next.