"Original Estimate" and "Remaining Estimate" get blanked when moving a Jira from "Open" to "In progress"

When we drag an issue from the 'Open' to 'In progress' swim lane the values of 'original Estimate' and 'Remaining Estimate' are wiped. The value change is shown in the history of the Jira afterwards.

This only happens in Greenhopper. When the same transition is done on the Jira directly this does not happen.

Also, it only happens on one particular project. Other projects do not seem to suffer from this.