Not able to view Knowledge articles based on User group

Summary:

Hi Team,

We created a new knowledge user group called "External Users" and created an article, tagging this user group in the article.

We also created a custom role called and provided the necessary data security policies by adding the reference key of the knowledge user group. Then, we assigned this custom role to a user.

However, the end objective wasn't achieved. The user should only see articles that belong to the "External Users" group, but they can see all the articles.

Can anybody help us resolve this unexpected behavior? Please share your inputs on this if anyone has encountered this.