It may be just too young for the dorsal "edge" to develop.
And because they are line-bred, inbreeding (especially if attempting more and more blue) may be deselecting for the natural colors most Andinoacara display.
Although its really not possible to determine age in a photo, a full grown EB Acara, may reach 6"-7".
But there are many factors that determine how fast a fish in an aquarium grows to just guess (too many tank mates during grow out, frequency of water change schedule, (or not) that remove growth inhibiting hormones during the growout phase, and/or deleterious nutrient buildup, also to do with water changes)