Spiratest issues do not sync with correctly Jira

Spiratest issues do not sync with Jira when non mandatory fields are filled in during creation of spiratest issues. 

When an issue is created in Spiratest and only the mandatory fields are filled in it works, after the creation if you fill in the non mandatory fields they get synced without any issue. 

The error in the system event log says: 

Error Adding SpiraTest Incident to JIRA: An item with the same key has already been added. at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean ad

Event Details

Exception:

Error Adding SpiraTest Incident to JIRA: An item with the same key has already been added.at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean adError Adding SpiraTest Incident to JIRA: An item with the same key has already been added.at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)at Inflectra.SpiraTest.PlugIns.JiraServerDataSync.DataSync.ProcessIncident(Int32 projectId, SoapServiceClient spiraImportExport, RemoteIncident remoteIncident, List`1 newIncidentMappings, List`1 newReleaseMappings, List`1 oldReleaseMappings, Dictionary`2 customPropertyMappingList, Dictionary`2 customPropertyValueMappingList, RemoteCustomProperty[] incidentCustomProperties, RemoteDataMapping[] incidentMappings, JiraProject jiraProject, JiraManager jiraManager, String productName, RemoteDataMapping[] severityMappings, RemoteDataMapping[] priorityMappings, RemoteDataMapping[] statusMappings, RemoteDataMapping[] typeMappings, RemoteDataMapping[] userMappings, RemoteDataMapping[] releaseMappings, RemoteDataMapping[] incidentComponentMappings)at Inflectra.SpiraTest.PlugIns.JiraServerDataSync.DataSync.Execute(Nullable`1 lastSyncDate, DateTime serverDateTime)