Clean up CSV, leave only needed columns (fields), e.g. Issue Key (for future mapping Jira issues), Summary, Checklists, Smart Checklist Progress
if issues from more than 1 project are to be imported - then leave Project column in CSV
Go to System → Import and Export → External System Import → CSV
Choose CSV file
map Issue Key CSV field to Issue Key Jira field and check 'Map field value' (by that field values will be taken for updating a ticket)
map Summary CSV field to Summary Jira field
map Checklists CSV field to Checklists Jira field, however, make sure to leave 'Map field value' checkbox empty! Otherwise, checklist value won't be imported
Always do test runs on test issues/values!
7. Once the import is finished - "Checklists" custom field in proper Jira Issues will get updated with Checklists values from CSV
For Smart Checklist versions lower than 5.0.0
If you are importing checklists into issues that may already contain checklists - you need to additionally sync "Checklists" field with com.railsware.SmartChecklist.checklist issue property, which now is the main data source.
Set proper JQL function to update only the needed issues
"Set entity property" Action to update "com.railsware.SmartChecklist.checklist" from "Checklists" custom field
Save the Function and make sure it is enabled for a short time that you need to actually sync the values
Once you proceed with Bulk import - "Run Rule" manually
That way your current checklist will get data from imported CSV based on the "Checklists" custom field
We are working on implementing the easiest way to synchronize checklist storages. So update of the "Checklists" custom field will automatically trigger checklist update even if there already were some values present.