Query 4390Q arises when a staff member has a Destination Code entered on their contract, but no contract End Date. Click on the Query to take you to the staff profile, then click on the cog next to the staff contract.
Check whether the contact has actually expired, which requires a Contract End date, or remove the Destination on Leaving (by selecting None from the dropdown). If there is a reason why an end date cannot be supplied, write a note when you upload the Census to COLLECT. Click Update to save the information on the contract, then return to recalculate the Workforce Census.