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It's a known issue for SEP 12.1 RU4 (12.1.4013.4013)
Cannot generate quick risk reports
Fix ID: 3044591
Symptom: When you try to generate quick risk reports, PHP errors and warnings display. You also see many PHP-related errors in the reporting logs.
Solution: Validated the PHP variables to resolve this condition.
But it sems you face the similar issue in SEP 12.1 RIU4 MP1 (12.1.4100.4126 ) version
The new SEPM build is labeled RU4 MP1a with a version number of 12.1.4104.4130.
If issue did not resolved with the latest versoin need to contact support team.