The forecast suggested due date in ASCP workbench is not displaying correctly

In one of our test environments, we are seeing that the forecast due date is being populated with the Plan Launch Date in the Planners workbench, for one month only, and then the remaining suggested due dates display as expected.

Demantra shows the forecast for January, February, March etc.  When we publish the forecast to ASCP, and launch the Plan, the suggested due dates for the forecasts show as the Plan Launch Date for February only - the dates for March onwards show correctly.

Why could this be?

Thanks.