Check the simple things first; are you sure the invoice number field is squarely inside the portal boundaries, with a bit of a margin?
If it's not that a bit more detailed info would be helpful about which TO the layout is based on, and which TO the portal is based on.
I am made sure the field is square with the portal. I even played with the margins a bit just to make sure so it is not that. Now, I am going to sheepishly expose the depth of my ignorance by saying I don't know what a TO is but I will assume it has something to do with the layout so I will walk you through what I have done there.
That layout is using the Customer's table as it's source. The Customer ID and Current Balance are pulled from that table. The name, address and phone number (the latter two I edited out of the photo for privacy's sake) pull from the address table by its association to the Customer's Table. The portal is pulling from the JrnlRow table to display the Inoive field. The Layout format is using the "Report" template.
The Table Occurrances (TOs) are the blocks you ceated in the Relationship Graph; ;Address', 'Customers' etc.
Your description sounds correct. (Did you change the field-name-style from CustomerIndex to CustomerRecord in the Contacts Table?)
Your screenshot has the field in the portal quite tight to the edge of the portal. Even a pixel the wrong side of the boundary will throw it.
What happens if you add a different value to the portal?
What happens if you create in the Customer Table a calculation:
Count ( JrnlRow::InvoiceNumber ) (return result type 'number') ?
Ok, after doing a rapid google crash crouse on how to actually do those things, I have indeed found the solution. It was my misunderstanding of the portal boundries. You were correct from the start. I assumed it had to fit in the entire portal window. My calcuation field also lists the number occrances of invoice numbers correctly. That's for teaching me that, btw. Should come in useful in the future. So, it was a glitch in me, not the program. Thanks for your help, bro.