File Upload Improved - Unique FlowGuide Not Working for Guest User

[rochellecurrier-dot]

Steps to reproduce

Steps to reproduce the behavior:

1. Go to public portal page as guest user where flow is embedded.
2. Move through screens until you get to Add Expense screen. Upload file and add expense.
3. This sends you back to a previous screen that lists all Expenses. Click Add Expense again.

Expected behaviour

The file upload should NOT be prefilled with the file that was uploaded on the last visit to this screen.

Actual behaviour

The file from the previous screen is prefilled in the list.

• When I run the flow in Debug mode as the guest user or when I run the flow as a standard user, the file is NOT prefilled, so it seems to be a permissions issue.
• In the flow component, I am using a unique {!$Flow.InterviewGuid} formula: {!$Flow.InterviewGuid}&TEXT({!varN_FileCounter}). After each file is uploaded, I am adding 1 to the varN_FileCounter variable, which makes the Guid unique every time they add a new Expense. Since the formula wasn't working as a guest user in the portal, I tried assigning the formula to a variable and using that for the {!$Flow.InterviewGuid} instead, but it also didn't work. I'm not sure if guest users have access to the Guid, even though the flow is run in System Context Without Sharing.