Why there are some particular fields not editable?
Some fields are grayed out, and cannot edit.
It could be due to the following reasons:
Those custom field types may not be supported in this app
Those fields may not exist in ‘Edit issue screen’ of Jira
If a row (issue) is entirely grayed out, there seems like to be other reasons:
User don’t have ’Edit issues’ permission for the issue
Workflow is customized (i.e. jira.issue.editable)