Date value in workflow is incorrect

When I assign a index field value of type Date to a Workflow variable, the result value is incorrect, for example:
index filed value = 11/15/2020
Workflow global variable = 01/16/0001

Note that date format here is MM/dd/yyyy, I tried changing the date format but still the results is the same.

What could be the problem here?

Apparently this is a bug in Workflow Manager test feature, workflow works fine with real data.