My Portal screens, including "Back" button actions were copied from another account and are identically set up. However, the portal for the account I copied from isn't having any issues and I can't remember experiencing this just last week when I was testing, but focusing on other issues.
Each "Back to Home" link has 2 actions:
1. Assign Value to Action Result (selects Value from Session > Portal - User Record ID)
2. Go To Screen (has the specified Active Record ID from Action Result above)
In your response, it seems like using a Go To Tab Link is a better option, but I tried changing action #2 to Go To Tab Link, but it produced the same results. Also, it makes no sense that these actions work in another portal.
Any ideas on how to fix it without having to start my customization over?