Take the following steps to resolve this issue:
1. Login to the ISC.
2. Navigate to Security -> Global Security -> Single sign-on (SSO).
3. If "Interoperability Mode" is enabled, then you must specify the case-sensitive default names of "LtpaToken" and "LtpaToken2" for the
"LTPA V1 cookie name" and "LTPA V2 cookie name" fields respectively.
4. Synchronize the nodes & restart Connections.
[*Please note that the Help tips for these fields contain the incorrect case of "LTPAToken" and "LTPAToken2".
This defect is documented in the following APAR, which is due to be fixed in WAS FixPack 188.8.131.52:
The information is from TN 1635025