Jobs remain in [dbo].[ACT_RU_JOB]

**Describe the bug**
We are experiencing problems with our Async Job execution. Jobs remain in the ACT_RU_JOB Table for long time and are not executed.
A call to Rest endpoint /service/management/jobs shows all this jobs.
Only a post to "execute" the the pending jobs frees up the list.

**Expected behavior**
Job queue should be empty

**Additional context**
the problem was happening on 6.7.2, we also tried to update to the latest snapshot and it is happening again.
The flowable cluster is running on Kubernetes, with 2 Rest nodes and 1 node dedicated to async job execution (FLOWABLE_ASYNCEXECUTORACTIVATE=true)