Hello!
I have a project I am making for a Windows platform on a Windows machine and everything works fine there, but recently I decided to build that project for Mac as well. So I transferred the project on to my Mac. In the editor, it all worked fine, but after I packaged the project it just won’t start. When I start it, the process appears in the taskbar, but no matter how long you wait, the game window doesn’t open. No crashes, errors or warnings, though. Firstly I thought that my plugins could do something wrong (Victory plugin and my custom one), so I disabled them, but nothing worked. I’ve tried resetting the project settings, switching the starting map, resetting all the plugins, but it seems like the problem isn’t there. Not only I tried one type of build, but all of them (Development, Shipping, For Distribution).
I tried building an empty project, as well as an empty project with just my plugins, and they both worked fine.
I tried to search for the game’s logs, but I couldn’t find them, nor the logs from the editor or the build tool (I searched through all the locations they could possibly be, according to UE4 Documentation and some answers on the Answer Hub).
Lastly, I’ve tried starting that build from 3 Mac computer with all the same results.
I am going to try to disassemble my project piece by piece now, and would appreciate any help!
If you start the game from the terminal you might be able to see some more useful information about why it is not starting correctly.
Assuming your project was called “MyProject” you can do this by going to navigating through the folders MyProject/Binaries/Mac/ and right clicking on MyProject and then “Show Package Contents”. Then navigate through Contents/MacOS and right click on MyProject and “Open With->Terminal”.
Or you can run ./MyProject/Binaries/Mac/MyProject.app/Contents/MacOS/MyProject if you are familiar with using the terminal directly.
Oh, yes! I discovered that right before I read your message! 
I have a bunch of build iterations saved. So the first iteration (the point at which this problem was discovered) says “exit;” right after it starts and then nothing else, but the process remains. The last iteration where I tried to reset all the settings to default, suddenly started working! Iterations in between get stuck on “Initializing movie player…”.
I guess I’ll start resetting the settings to the master project state and try to figure out what caused the problem.
Thanks for the answer, anyway!
PS
Forgot to mention that the first iteration was For Distribution, so no wonder why there were no logs.
The problem is completely solved!
I guess there is no borderless mode on Mac OS, so remember to DISABLE “Use borderless window” option in the project settings before building for Mac!
P.S.
This cost me 5 days to solve…
You are wonderful and spare us tons of time!!! <3
Darn. I’m having the exact same issue, but borderless window is not checked in my project settings. I know almost nothing about Macs so I have no idea how to trouble shoot.
I ran the project in terminal and this was the result: