Same issue here. Same process. Also uninstalled a working copy of xcode to free up storage but now I can't download 12 (non-beta). My guess is that it has something to do with cache, app store, busy servers or something simple. Even after freeing up space I received this message with 70 gig available on old 2012 Catalina. If only this could have been updated versus a complete install. Didn't keep the previous downloaded copy of xcode.
mtmdev
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