X Code 12.4 displays no simulator after I select it

Hi, I've noticed that when I do a search, the results for a problem like mine are about 5 years old, which is terrifying.

I'm running Big Sur 11.2.3 and I've downloaded (again) X Code Version 12.4 (12D4e). When I choose a simulator (like iPhone 8 to match my own phone, for example), the dropdown is there, and yet I never get a simulator to appear.

This is my first time working with Swift/ X Code, and I'm trying to follow a tutorial on You Tube. I know exactly what I'm missing, since the guy on the screen has a nice mockup of an iphone that displays what he's typing, while I don't have anything. I've rebooted my Mac and I've deleted/ reinstalled X Code.
X Code 12.4 displays no simulator after I select it
 
 
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