Software Update For Mac Not Showing Up. You might need to check a few things. Open the Mac App Store from your Dock or Finder.
Go to Settings on your iPhone Tap on General Then tap on Software Update It will start to search and check update and generally will show you the iOS 14 update Tap on Download and install. You should see a message telling you that Big Sur is available. Also ensure than your Macbook if it is a Macbook it is plugged it into AC power.
Once your Mac is enrolled in the Developer Beta Seed you should see Beta 2 show up in Software Update or in terminal via softwareupdate -l If software update still says No new software available.
Check the Uptime of the Apple Servers Soon as Apple rolls out an iOS update millions of people start downloading it right away. You might need to check a few things. They occur especially when requests for updates overrun the Apple server during the early days of the macOS update release. You might need to close and reopen System Preferences Software Update.