Parallel Multi instance call acticity issue

Hi Team, We are having the diagram which holds the call activity sending List of accounts into one by one. In the child Bpmn we are performing some service task. Now sending around 300 records in the callactivity . But it is processing few and then just stuck it is not picking the job workers.
Parallel Multi instance call activity

Can you give some more details about the worker you’re using and how long it takes for a worker to finish a single job.

Also - have you tried spinning up multiple workers for this job?

can you please tell me how to spin up multiple workers for this job.