@DizzyDizzyDiana No worries. This forum can be a little difficult to navigate at times. I'm glad you found it 🙂
When you dragged the food to your toddler, was it a full meal? And did you have the toddler grab a serving? Does the toddler cancel that action?
Edit: After doing a bit more research and reviewing your post (along with others having similar issues), I'm convinced the issue is autonomy. It's possible others may disagree with me but I wonder if you might disable autonomy for as long as it takes to get the toddlers aged up. There are known issues across multiple posts indicating sims interrupt actions to complete other autonomous whims. This includes toddlers. Even if you manage to direct a sim to feed the toddler, the toddler may gain his or her own whim which can also interrupt the action. So, my advice is to go into your settings and disable the gameplay autonomy. Basically, from the triple-dot settings menu, select Game Options then Gameplay and set autonomy to Off, as well as check the box to disable autonomy for the active sim. This will prevent those whims that interrupt directed actions. This way your adult / teen sims complete care actions that you direct and toddlers complete eating and other actions. Of course, that means you have to direct your sims to do other things but only until the toddlers age up. Then, hopefully, you can re-enable autonomy and sims will care for themselves. I also would like to again encourage you to click "me too" on this post because I think it matches your issue. [OPEN] Parents refuse to care for toddler - Answer HQ (ea.com)