Started by user is coming as null


i am using flowable 6.2 . I noticed a strange thing. i started a process with a user with basic authentication using runtimeService.startProcessInstanceByKey(). Now 1st time startedBy user got set in db. i completed the process. now when i started the process with same user again, started by user was set to null. i tried multiple times and every time it was set to null. Now my use case is that 1 user can have only 1 process instance running. so when ever user login, i run the following query to check if he has any process instance


and it return empty list because startedby user is set null but user appears as participant in that process instance as tasks are assigned to him and so new process is started every time on login. Also i have exposed a url to see all the process variables in the process for a developer user “dev-user” and sometimes startedBy gets set to “dev-user” in database. Is this some bug or what?

Thank you,
Arpit Agrawal