One thing to watch specifically with vegetables, since it catches people the first time: they float much more than meat does.
Raw vegetables trap a lot of air in and between the pieces, and more comes out during cooking. A bag that sat obediently underwater at the start ends up bobbing with half its contents above the surface, and the exposed part is simply not cooking. If your carrots were partly out of the water, that is a second reason for the result even after the temperature one.
What works, roughly in order:
A heavy object in the bag. A spoon or a small ceramic weight next to the food. Simplest and most reliable.
Something over the top. A rack or a plate that keeps the bag under.
Clip the bag to the side so it cannot rise.
Magnets and clips sold for this work fine too, and none of it is better than a spoon.
At higher temperatures there is a second effect worth knowing: more evaporation from the bath, so on a long cook the water level drops and can expose things. A lid, a cover, or even a layer of ping pong balls handles it, and it also stops the machine working harder than it needs to.