Flow does not continue after FlowableOptimisticLockingException

**Describe the bug**
Given the flow below, we experience a problem with concurrency when executing the “simpleLog” (async) service task in parallel with cardinality = 5, after which the flow does not continue with the “dummy” (exclusive) service task of the next step nor retry the job in “simpleLog”. Instead, we get 4 FlowableOptimisticLockingException.

What could be wrong here? Should flowable retry 3 times after FlowableOptimisticLockingException as we have read here: https://flowable.com/open-source/docs/bpmn/ch07b-BPMN-Constructs/#fail-retry ? Why the flow does not continue?

**Expected behavior**
To be detailed, “simpleLog” only prints some hardcoded string, sleeps 3 seconds (to simulate a real task) and shows another hardcoded string. “dummy” shows another text and “finalLog” shows all global variables.

**Code**
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5

```

**Additional context**
Flowable version: 6.4.2
Database vendor: Oracle
We are using Flowable with Spring Boot