Invoice positions disappear from Portal
I have a layout "Invoice" to invoice my clients with the various services that I provide.
I am using a portal to display the various "Invoice positions" in my Invoice layout.
When I create a new invoice I create the Invoice positions within that portal. I enter a description, quantity and price for each position one after another. Often I enter a few dozen positions, while the total will be computed at the bottom.
Everything seems to work ok. Until I click outside the portal with my mouse (which happens inevitably at some point). When I do that, all my Invoice positions disappear as if by magic.
Technically, they are still there; I can find them in the "Invoice positions" table when I look for them. However, I can't get them back into my layout and have to start from scratch every single time.
What am I missing here?
Thanks for any help.