What happens in File Explorer if you do the same thing?
What kind of drive is it?
Opus gets the directory listings from the operating system, so if the listing is loaded after the drive is formatted then the operating sytem must be returning the old data.
If, instead, the issue is that the drive listing was already visible, the drive was formatted, and the file display not refreshed, then that could be different. F5 to refresh the drive may fix things if no change notification triggers an automatic refresh. See also Changes to folders are not being detected for other things to try.