I don't know why, but Trailhead does not see that I've setup a user Samantha Cordero with the profile Field Sales User. I've create the Field Sales User profile, created the user Samantha Cordero, activate the user, generate a password, and logged in as the user. I even logged in as her in Salesforce 1, but I still get this message:

Here is what her user detail page:

Field Sales User profile:

I'm trying to complete the "Set Up Single Sign-On for Your Internal Users" Trailhead challenge, and was able to execute the description of the challenge successfully. However, I'm getting the following error when checking the challenge on Trailhead:
 

Challenge Not yet complete... here's what's wrong: 
Could not find SAML Enabled in your org's setup audit trail. Make sure that you have 'SAML Enabled' checked under 'Federated Single Sign-On Using SAML' in your org's 'Single Sign-On Settings'.

I've reviewed the settings, and "SAML Enabled" is true, and I'm connected to the right org when doing the challenge. Has anyone else encountered this?