*Usually* the pale bottoms are caused by excessive mushrooming of the top - when the canele expands upwards, if it also expands outwards, the wider top no longer allows the pastry to slip downwards in the cup when the temperature is reduced. That leaves a gap at the bottom. An insufficiency of lubrication (butter/ beeswax) can also prevent the slipping and thus leave it hanging. In your case, I don't see evidence of mushrooming. So, either you have insufficient lubrication, or too much. Too much pools in the bottom, and so you don't get the browning.
I think the main reason most people freeze the molds is to lock the lube in place. You have a tension going on - the cold mold is heating, the batter is heating and expanding, the hot air on the top of the batter is starting to harden it. It's a race - ideally, the top hardens such that the pastry cannot expand outwards, but still expands up, and the lubrication on the sides allows it to expand upwards. Then the heat fixes the shape, and when you reduce the oven temperature the pastry contracts slightly. The sides of the mold are sloped, so the pastry can drop lower in the mold as it shrinks. Again, you want enough lubrication to allow this, so that the bottom of the pastry gets in contact with the bottom of the mold.
The one thing you can control once they are in the oven is the time when you reduce the temperature. Do it too early, and they collapse because they aren't rigid enough. Too late, and the pastry in stuck where it is. If you avoid mushrooming the heads, you have some leeway as to when you drop the temperature.
Happy baking.
PS Those first ones indeed look perfect. And I bet you ate the second batch with no problems either!
