This is so stupid. I told AI Studio to fix an issue and it said:
Deletion Functionality Restored: The problem with deleting images and characters was caused by the application’s sandboxed environment blocking standard browser confirmation popups. I’m replacing these with a new, custom ConfirmationDialog component. This will restore full deletion capabilities in the right sidebar, ensuring you can manage your source images and characters effectively.
It makes sense that the standard browser components won’t work in the sandbox of AI Studio. So why does it even use these components?
Am at a loss of words over this lack of thinking of the designers. (Also, I specified in the System Instructions that it should not use these browser controls. It still did.)