Customer has indexed assertion consumer Service (ACS) URLs configured, but every assertion is posted to the default ACS URL.
The Service Provider software doesn't support the AssertionConsumerServiceIndex parameter for SP-initiated requests, thus indexed ACS URLs cannot be used. Only one default ACS URL will work in this scenario.
Release : ALL
Component : SITEMINDER - FEDERATION
The SP needs to include the AssertionConsumerServiceIndex parameter in SP-initiated requests in order to utilize indexed ACS URLs.