Why are Salesforce fields not showing up in the Jira mappings?
When trying to map Salesforce fields into Jira, the fields are not showing in the mappings screen.
In normal cases, the issue is explained in detail in this documentation: Salesforce custom fields are not visible for mapping and is related to a formula field based on a child object which is not supported as mentioned here.
If the knowledge base above do not solve the issue for you. The next solution to try is to check if the profile of the integration user does have visibility of the fields.
Go to Setup > Connected Apps OAuth Usage.
On the page, look for Salesforce & JIRA Cloud Connector (or Salesforce & JIRA Server Connector depending on the case).
In the User Count column, click the number and click on the user.
Check and make sure the profile shows "System Administrator".
Next, go to Setup > in the Quick Find Box search for Object Manager and click on it.
Select the object with the fields that you want to map and click Fields & Relationships.
Click on the field name > Edit > Change Type File.
On the Establish field-level security screen, search for the profile of the integration user and make sure the visibility box is checked. Then, click Save.
Repeat "step 8". for all the fields that you want to see on the bindings.