We can't create a timeline for this report because it doesn't have a field formatted as a date

I have an excel 2016 pivot table that is using a data connection to an ssas 2012 Olap cube

When I try to add a timeline slicer I get the dreaded

We can't create a timeline for this report because it doesn't have a field formatted as a date

I do have an order date attribute that is defined as a date field on the dimCalendar table

I have done some research and found some possible causes

one possible issue mentioned is that the field may have blank or invalid dates.
(I double checked this is not the case in my data)

The other was that the field needed to have the

ValueColumn of the date key to use an actual date field from the underlying SQL table.  The KeyColumn is an integer and the NameColumn is WChar.  and to set the ValueColumn to use type Date

I validated this was true as well

Anyone have some other thoughts