I've done my best going through documentation and websites, but I can't figure out why portal records disappear after entry. The records in the underlying table do not disappear--they just don't show up in the portal.

I have attached the file. The layout in question is "Employees - Form View." Try selecting a project from the drop-down menu in the portal. You can enter data in the other fields, but once you finish, it goes away. You can check that the underlying record still exists by going to the "Assignments" layout.

Obviously, I want the records to show up in the portal after I have entered them there. What should I change?

CEMSE_Projects.fp7.zip

For starters, change the field 'Full Name' In Assignments from Number to Text.

A better solution would be to give each Employee and each Project an auto-entered serial number, and base you relationships on those. That way you can change the names without breaking the links.