CSV Import from Issues is unreliable

I found JRA-44147 which encompasses the general issue that I've been encountering but wanted to add some other info that I have noticed about it as well and raise the priority. Overall the new feature to "Import Issues from CSV" under the Issues drop drop down doesn't reliably import all the data from a CSV as the "External System Import" does from the System admin section. In addition to certain field being imported inconsistently, such as time estimates in the linked issue, there are many custom fields that will not successfully import using the Issues import method.

Importing issues from CSV files is a critical and frequent step in our projects workflow and we would like to avoid having to give so many of our team members admin privileges just for the ability to successfully import issues. Any help in resolving this would be greatly appreciated.

h2.Summary

I imported the attached CSV file (which contains a single issue with a 3hr 30min original estimate) using Issues -> Import Issues from CSV, and the new issue had an original estimate of 3 hours (see screenshot).

I imported the file using [Administration] -> System -> External System Import and the new issue had the correct original estimate of 3 hours 30 minutes.

I assumed the behaviour of both CSV importers would be identical.

User's description explains the bug the best. Basically there is a difference between the 2 importer and the value of the time fields are not

h2.Steps to Replicate

Create a new Agile project. Make sure that the Time Estimate field is added to the right screen and project.

Import using Issues -> Import Issues from CSV. Resulting ticket is refered as Ticket A.

Import the file using [Administration] -> System -> External System Import. Resulting ticket is refered as Ticket B.

h2.Expected Result

The Remaining and Original Estimate field is showing different value. Ticket B is showing correct value while Ticket A is showing wrong value.

Using Issue External Import

Using Administrator External System Import

The correct time estimate value is 3 hours and 30 minutes.

h2.Current Result

The Remaining and Original Estimate field is showing same value for both Ticket A and B.

h2.Note

There are no error logs from Jira log during the import for both tickets. I've included test.csv for testing/replication purposes.