I needed to have the Workflow message processing batch job running, but it seemed to be stuck ...
So, in order to have it running properly, I took a look at all the other jobs ...
Some of them had different statuses like Executing or Error from quite some time and I think that was causing the entire batch system to stop. I tried to pinpoint the exact problem, but since that was only my development machine and needed a particular batch job to run, I decided to clear everything and just recreate the workflow job. I initially tried to delete them from AX, but as you know some statuses do not allow a job to be deleted, so I went directly to SQL.
The solution (SQL script):
delete from BatchJob
delete from Batch