How to enable Custom ID Field ?
For Jira DC to enable Custom ID field refer to the following steps:
Open Issue Settings from Administrator Settings:
Go to Custom Fields option in the left panel.
Click on the Add custom field button, and select the Advanced tab and select Custom Id. After this click on Next.
Give Custom ID field a name (Please keep it as “Custom Id” for easy recognition). Click on Next .
Now you can see the generated Custom Ids in the issue screen. Please Make sure if you haven’t generated any Custom Id yet the field will by default not be visible on the Issue view screen even after enabling it. Hence please generate Custom Id first to view custom Id on a particular Issue.