The revision custom field must be a "normal" Jira custom field and not an issue field

Users can't rename the Revision custom field as it is LOCKED. This is because Xray implements the Revision field as an issue field.

This field must also be installed as a "normal" Jira custom field, allowing users to rename the custom field.

If there already is a custom field named Revision, Xray will create a field named "Xray Revision".