JWT Authentication Scheme fails to authenticate token with many claims and this is observed for the JWT token size over 4k .
The following output can be observed in this situation (smtracedefault.log):
Policy Server Version: SiteMinder 12.8 SP6
Upgrade Policy Server to 12.8SP8 when this one will be available to benefit fix from DE551905.
Defect fixes in the service packs, in this case 12.8 SP8, can be verified from the below link once it is GA,