Review the full blog post.

SUMMARY 

When you insert a specific (bespoke) field in a standard or bespoke table, make sure you insert your field in any updatable persistent class linked to the table if there is one, even if the class is standard.

Also, do not forget to sync the class properties when you make a class updatable.

This applies to all specific (bespoke) developments on tables that have classes linked to them, such as PORDERQ for example, or any table developed by you.

In short, when you insert specific fields in a table linked to a class, you need to make sure the class also includes your specific fields as properties.

Why? 

If the class does not contain all the properties linked to the table, you may lose the data linked to those missing fields any time the class and table are updated because missing fields will be reset (cleared) anytime there is an update operation.

This information will be added to the Upgrade and Development documentations.

Note: This is not a defect.