Not really an answer but also have the same issue and its Oct 2020.
Have a Mac Pro, takes too long to start, MY PROJECTS don’t show.
Using same on a work PC/ Windows 10 which is flaunt with issues and it works like a charm.
Have tried apps to remove entirely anything to do with Unreal and re-installed with same issue.
This is happening to UE 4.25.
I have XCode installed also with no change, concur that the in the background it is running a process which really slows the launch down. Trying to compile something.
The MAC Pro I have is no slouch, Foundry Modo runs fast along with all the Adobe suite, Final cut pro etc…
Wow some issue. Can we please get a response on this.
I can’t use Unreal for a project at all.