I've had this as well.
Playing TEC (R) vs TEC
The scouts would not reveal the mines - it just keeps auto-casting reveal mines (even in range of them) and the game does not remove the invulnerable tag from the mines - I've also noticed that I can't turn auto-attack off on my scouts either.
I tried a full fleet containing scouts as well a seperate scout fleet - both had the same problem.
I had to use a Titan to 'smash' my way through a reasonable mine field - as you can imagine, its not the best way to clear them!