Microsoft SSO SAML Assertion Claims

Yes, user.country is supported as a SAML claim source. Your screenshot maps that attribute to an outgoing claim named region; naming the claim region does not convert its value into a full country name. Microsoft also documents country values such as US, so receiving a code does not by itself indicate an unsupported attribute. First, inspect the country property of the exact user signing in, in the tenant containing this enterprise application. Do not confuse it with usageLocation, which is a separate property. Save the claim configuration, start a fresh sign-in, and inspect the actual region attribute in the resulting SAML assertion before the application processes it. If the assertion is correct but the application displays something else, investigate its mapping. If a different representation is required, configure an appropriate supported transformation or directory extension. Share only redacted claim details, never the complete authentication token.