[Alneyan]

The same thing happened to me once against the AI, as one of their ships managed to get in the same sector as a mined planet without any problem. However, it was an AI, so it could be one of the peculiarities linked to the AI. (Such as its ability to build facilities on the turn it colonizes a planet)

There was nothing like entangled minefields however, so if both events are linked, it may mean that there is *something* lurking in how mines are handled by the game.