Challenge not yet complete in My Trailhead Playground 1 -> We can’t find a user with their Username including ‘testuser’.

Hi Trailhead Community,

I’m facing an issue with the Trailhead challenge “Create a New User and Deactivate It.”

The challenge requires me to:

•  Create a new user with the Minimum Access - Salesforce profile 
•  User License: Salesforce
•  Alias: testuser
•  Username containing testuser
•  Deactivate the newly created user 

I have completed these steps multiple times in my Trailhead Playground, including creating the user with a Username such as:

ktv_testuser_20260930@example.com

I also verified that:

•  The Username contains testuser
•  Alias is testuser
•  User License is Salesforce
•  Profile is Minimum Access - Salesforce
•  The user is deactivated/inactive
•  I am checking the challenge against the same Trailhead Playground where I created the user 

However, when I click Check Challenge, I still receive this error:

I have recreated the user multiple times and verified the Username and other required settings, but the challenge still does not recognize the user.

Could someone please help me understand why Trailhead is unable to detect the user or whether there is an issue with the challenge validation?

I can provide screenshots of the user configuration and the challenge if required.

Trailhead Playground: My Trailhead Playground 1

Thank you for your help.