This is still happening on Mac OS Big Sur and Xcode 12.2 stable I cannot preview any swift ui view in my application, and it was working just fine before the update. Does anyone have any suggestions?

In my case, changing the product name seemed to help, although I'm not completely sure that was the problem as I changed a lot of things while trying to make it work. (the name was starting with a number and I removed it on debug target)