Queue cache old process

Hello Community,
I have been using CI4 Queue add-on to process some jobs, however I have been facing strange issue with the job process when it fails and retry.
for e.g. A job has been added to queue and it fails. Now suppose some changes made into code and the failed job again added into queue but this time the new code changes doesn't reflect into process. The outcome is still same, the new changes only reflects if the fresh job added into queue. I don't understand why and how the old code executes in case of retry?
Also the Skip locked feature giving fatal error, I have 10.4.32-MariaDB
is this possible to run multiple concurrent jobs without affecting main application?