It appears to be related to building the "Share..." submenu since selecting "Share..." from the File primary menu has a similar delay. In each case the result is Messages and Notes, so it doesn't seem very exotic.

Using Xcode 10.5 on macOS 10.15.5 and trying to notarize a Cocoa app for out-of-store distribution following this - https://developer.apple.com/documentation/xcode/notarizing_macos_software_before_distribution?language=objc and this - https://help.apple.com/xcode/mac/current/#/dev88332a81e and what I see doesn't match the instructions. First, there is no "Distribute App" button, but there is a "Distribute Content" button. I assume that this is because I have both an app and a helper tool, so I'll try not to worry. Second, clicking "Distribute Content" brings up a dialog with "Build Products" and "Archive" but nothing related to "Upload", "Mac App Store", "Developer ID", or "Development" as shown in the instructions. Why not? I've looked at the possible issues - https://developer.apple.com/documentation/xcode/notarizing_macos_software_before_distribution/resolving_common_notarization_issues, and confirmed that my app has a valid code signature ("valid on disk", "satisfies its Designated Requirement"). If I run the app with right-click run, then it launches and runs fine, so I think it has a valid developer certificate. I understand that the the timestamp is generated by the archive process. I think I have enabled the hardened runtime. Thank you for your time.