Since 8.19.1, Jira has introduced a new mode : OPTIMISED_USER_LOOKUP.

It changes the way the Users are identified for Permission Scheme with a more efficient way (response time), but it causes also inconsistencies in results ...

See :

• https://jira.atlassian.com/browse/JRASERVER-73406 
• https://doc.alkaes.fr/display/ALKMW/User+By+Workflow+Step

The JVM option com.atlassian.jira.use.optimised.user.lookup is injected when the settings is set toy YES.