After updating to 4.10, and subsequently using the xcworkspace, I noticed that if I run the Clean command from within Xcode, it ends up deleting core engine dylib’s and renders the global installation of UE 4.10 useless.
After this happens if I hit Verify on the 4.10 installation of the Engine/Editor from within the Epic Games Launcher. It downloads some stuff, and allows me to use the engine just fine.
To be clear, this is a global installation of 4.10 not a source checkout, running a C++ Project with a generated Xcworkspace.
Note that this issue was also listed among the grievances in this question. This is a separate issue than splitting the monolithic project into a workspace (which is great), it appears that Product->Clean in Xcode also runs Clean unconditionally on the UE4 project included in the workspace, which causes critical engine files in /Users/Shared/UnrealEngine/4.10 to be removed.
As thejustinwalsh mentioned, the only way to recover from this is to run the Verify command in the Epic Games Launcher.
I was able to reproduce this on my end and have entered a bug report (UE-23624) to investigate this issue further. Since running Verify does seem to fix the problem easily I would continue using that for the time being.
This happened to me 3 times and I wondered why the engine suddenly is missing dynlibs. So it’s the Clean. Good to know. A Verify restored successfully. I’m on 4.11.2, this bug needs to be fixed.
This is still happening (for me at least) on Catalina 10.15.4, Xcode 11.3.1, with UE4.24.3. I see that Unreal Engine Issues and Bug Tracker (UE-23624) is closed as a duplicate. What ticket is a duplicate of? I’d like to follow the progress there and help out if I can.