"Missing required export fields:..."
If you see this message when trying to set an Order's Export Status, it means that certain fields have not been completed as required for this Showroom.
Simply make sure the required fields are completed and then try setting the Export Status again.
Disable Export Requirements
If you wish to proceed without completing these fields, you can disable specific requirements for Export in your Order Settings.
You can check/uncheck the checkboxes for each field to set/remove them as required fields.