Object Workflow Not getting triggered for few users- Groovy

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We have a Object workflow -groovy being triggered based on a condition on Update of a record in a custom object. The groovy code is being triggered for few users and few other users it is not triggered even though the same process is followed and the condition is satisfied. Is there any way to debug why the workflow is not triggered for few users as the user does not has access to sandbox and we can not enable the same.also the Run time messages are not displayed when tried from Object workflow groovy code. 

Also, is there any role required to be added for users to get the Object workflow invoked.