Did you complete the milestones gradually?
Are the preceding required milestones correctly displayed in the Milestones Pannel? The order is Learned to Walk > Learned to Climb Stairs > Learned to Dance > Learned to Run > Maxed Movement Skill. Specifically for Maxed Movement Skill the toddler needs to have achieved Learned to Run.
I tried in one of my test saves. Had a toddler master the movement skill by using the building blocks. He successfully achieved the Max movement skill after achieving each of the intermediary milestones.
How is your toddler learning the skill? Using a particular item or by walking/dancing?
