Festool router collets are 2 step. Meaning when you loosen the collet, it will come loose then feel tight again. You have to keep loosening it past that point to get the collet to fully release the shank of the bit.
welcome to the fog.
the above is true and probably the issue but sometimes this happens to me. i open the collet nut both time but the bit is still held. i find that pulling the bit doesnt help . i find pushing the bit back into the collet first solves the problem. it will pull out easily. this also happens on my dremel
