External link blocked without warning

1 - Sandboxie 5.3064 bit , Windows 10 Home 1903 x64
2 - Second Life viewer latest version
3 - F-secure and Malwarebytes latest versions
4 - Steps to reproduce the issue:

The Second Life chat game allows to download content that is packed in a "box"
The "box" has to be opend which shows a pop-up with the content, but the content isn't shown in Sandboxie
If run outside Sandboxie it works fine.

How do I configure Sandboxie to allow the pop-up to access the internet to the Second Life Marketplace that holds the content?