This 0% value calulates the employee as 0 weekly hours. 

So lets go through the process to update the FTE % and then therefore the weekly hours.  Click the pencil icon, top right of the employment tab.

There is where you can customise the relevant working patterns of an employee

The "Site Default" forces the standard working pattern of the employee. IE Australia is 38 hours per week, 7.6 per day. 

Removing Friday work calculates and employees FTE % to 80%

When you save, the FTE is now"80" and the weekly hours are now "30.4"