Summary

Using JIRA's CSV Import feature, when user import a CSV file with default time tracking time set to anything other than minutes, JIRA displays wrong value for the estimated time. This issue can't be reproduced if the the CSV import is done using the External import feature.

Exemple:
(CSV) Original Estimate = 2400 seconds
(JIRA) Original Estimate = 1 hours
(the correct value on JIRA would be 1.5 hours)

Workaround

Importing for External Import function will import the CSV file with right time tracking value.