This is now working in Cloud.
Only, the resolution dates are not imported/updated from CSV if you do not import/update the Resolution field as well.
As per the "Is there a way to change the "Resolution Date" thread in the Atlassian Community, in order to update the resolution dates you need a CSV file with at least the below 4 fields:
- Issue Key
- Resolved (to be mapped to "Date Resolved")
Import from CSV does not update Resolved Date field
Steps to Reproduce
Prepare CSV file to include a Resolved Date field
Go to External System Import > Use Jira Import Wizard > https://<instance>.atlassian.net/secure/admin/ExternalImport1.jspa
Choose CSV > Import CSV file created in 1
Define date as included in CSV and click Next
Wait for Success message
Resolved Date Fields are updated with CSV values