AdministratorAccess isn't working for users/user group

I - the root user - created a user group with (1) user. I gave the user group one permission which is AdministratorAccess. Looking at the json policy, it appears this gives all users within this user group access to any and all services on AWS. I signed in as the one IAM user and attempted to access Billing and Budgets. I wasn't able to access either, nor could I access cost explorer. I attempted the following:

-removed the user from the user group, then added the user back, giving it the permission for AdministratorAccess. -I added the BillingFullAccess permission to the user - not the group. I tested it out, I still wasn't able to access Billing, Budgets, nor Cost Explorer. I removed the permission and kept AdministratorAccess as the only permission for the user group. -I created another user, added it to the user group with AdminstratorAccess.

All of my troubleshooting attempts were in vain and I'm still unable to access Billing, Cost Explorer, or Budgets as an IAM user. Any ideas on what I should do to troubleshoot through this? Also, I am on the free tier to learn AWS.