Issue Summary

Import is capable of adding new options to locked custom fields.
JIRA includes JIRA Importers Plugin (JIM). This is what provides the import functions seen in JIRA Administration "External System Import"

• This includes options to import from CSV, JSON, FogBugz, Mantis, and others.
  JIRA includes custom fields and the ability for custom fields to be "managed" or "locked." These are fields that are created by JIRA Applications or plugins. They are locked to prevent them from being changed.

Steps to Reproduce

Example problem caused by this behaviour

During import, the Epic Status custom field gets modified to include additional options. This causes JIRA Software boards to show epics that are marked as "Done"

• See Epics marked as Epic Status = Done continue to appear on the Agile Board for additional details regarding this behaviour.

Reproduced in Jira Cloud

• Create CSV for importing, including Epic Status and at least one issue with Epic Status of "Open"
• Import CSV through External System Import. On the field selection screen map the CSV Epic Status field to the Epic Status field in JIRA (do not map field value)
• Observe that the new option has been added to the locked Epic Status custom field. This "Open" option causes the behaviour described in the KB article linked above.

Expected Results

Locked fields cannot be modified by import. 

Actual Results

Epic Status field updated with the new "Open" status.

Workaround

Currently, there is no known workaround for this behaviour. A workaround will be added here when available.

See similar ticket for Jira Server and Data Center - JRASERVER-67230