My 1.5 year old isn't showing as a dependent that I can claim dependent care costs for - why not? She's listed as a dependent in the first section but doesn't show here

Have you entered any earned income yet ?   Until you do that credit will not populate.

Are you claiming the child on your return ?   Are you the non custodial parent who only claims the dependent and the child tax credit ?  

Yep, I have. It shows my two older kids but not that one. I have all her info entered and are filing jointly with her mom.

Ok ... so you are filing a joint return then go back to the MY INFO section and delete that child and reenter them again going slowly ... you must have made an entry error somewhere.