Date variable set to 1/1/1900 when target workflow triggered by calling workflow with Workflow method Start Workflow on List item method with association data

Steps:

- Call Webservice Workflow (StartWorkflow on List Item)
- has association data and encode inserted tokens is checked
- The target workflow has a date time variable myDate
- Issue is that the myDate value shows up in a Send Notification as 1/1/1900 12:00 AM even though the default for the variable is the current date.
- If I remove the association data variable from the calling workflow, then the myDate variable shows the correct current date.

 Why ????