This is very common issues many face on Jira. This happens when you add a new custom field on Jira and forget to associate the same with the workflow screen of Jira.
You can find the solution for this below:
Step 1: Go to settings > Issues
Step 2: Go to Workflow Schemes Under Workflow
Step 3 : Edit the scheme that require the new issue type to be added- say CC Internal Scheme needs to have Epic as an issue type. Click on Assign once the CC Internal Scheme edit page opens. Then click on Epic and then finish button
Post that- just publish the Scheme on Jira, and voila, you’re done!!