Why the default padding classes of tailwind css not working after I add a custimization to It?

After adding this custom padding class in tailwind.config.js

  module.exports = {
         theme: {
      padding: {
          yt: '56.25%'

I am able to use the class as pb-yt for bottom padding.
However the normal classes for padding which used to work doesn’t work now.
Eg : p-8 p24 px-4 pb-4 are default classes by tailwind which used to work before I added the custom class.
What am I doing wrong here?