It'd probably get in the way.
When it comes to animals that can change color there's usually 3 main methods:
1-the creature slowly changes the color of fur/scales depending on the environment and its age (most common examples are mammals which have completely white fur in the snowy winter and more brownish fur in the warmer seasons. This one is great if you don't need to constantly blend in with very different surroundings, and it's much easier to have
2-the creature has transparent coverings. Seen in chameleon scales, their skin isn't exactly exposed, but the scales aren't opaque, and allow their color changing mechanism to show well. This might be hard to implement with fur
3-no coverings, there's only the birthday suit. One key similarity between octopuses, squids and cuttlefish is that at most their skin will be covered with a layer of mucus. Particularly in octopuses and cuttlefish, their camouflage comes from a complex combination of color changing cells, called chromatophores and from a muscular layer that allows their skin to change texture to match that of the environment. These 2 factors are what give these animals their superb camouflage. I assume this is what you want your creature to be able to do.
The problem with fur is that, being basically a number of dead cell filaments, they don't exactly change color on demand, nor can they be finely controlled. That means that even if we were talking about hairs with no melanin, we'd still have the problem of white hair obscuring the color changing skin and be in inevitably moved around in potentially problematic ways as the skin morphed to match the texture of the background. Camouflage at its most basic form is about making it hard to tell where the animal ends and the environment begins and at its best making it impossible to tell there's not just environment there, and I'd say it wouldn't be hard to figure out that the tree chunk filled with white fur is not really a tree.
So, by default, if you want camouflage like that of a cuttlefish or octopus, you'd also need to compromise on the drawbacks of such pristine camouflage, such as the need for an uncovered skin as well as the need for a protective layer, since such a skin is normally a bit more fragile since it can't be too thick (also you're on the right track looking more at the cuttlefish, because the octopus' amazing camouflage gets a boost from its soft body, its lack of limiting hard structures allow it to further match the environment by reshaping its body to an extent).
So basically, it'd probably be problematic for an animal with a skin like that of the cuttlefish to have fir. If it doesn't participate in camouflage in any way, it gets in the way of the camouflaging skin, and the only way to fix that is to share the camouflage duty through hair pigmentation, limiting the skin's dynamic ability. A potential solution is that the cubs, being still young and inexperienced, have a layer of fur that matches its surroundings, both serving as protection to the more sensitive skin and protecting it from a potential accident where it takes on bright colors while still giving it camouflage capabilities. As the creature enters adulthood and reaches sexual maturity however, it slowly begins to loose most of the hair in its body, becoming more dynamic in their camouflaging skills. Chances are that the creatures seen with fur are still sexually immature juveniles in a tough spot because they still haven't lost all of their hair and are learning how to fully use their skin, which is why they're more easily spotted than the skilled adult stalking you.