FTE and Headcount is showing as 0 for rehire

Summary:

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We did a rehire and for this employee, Both Standard working hrs and working hrs are showing correctly as 40, But FTE and Headcount is showing as 0 in Person management> Employee page.

This is not position based.

Employees created before and after this employee are showing FTE and Headcount correctly.

We were able to show the FTE as 1, by changing the working hrs to 30 and then to 40 and save.

But, The Headcount is still showing as 0. The employee have only 1 assignment and it is a primary assignment.

Any insights to How to fix the headcount to show as 1?