If you compile the Unreal Engine by yourself, the first time you open it (just the first time), it will take a long time before run because it compiles shaders and does other stuff. Just be patient and you’ll see that eventually it will run.
I checked out 4.19 version from Github. I compiled the whole Engine and the first time I launched the editor it remained stuck for a while (I don’t remember how much it was but it was not a short time).
Try this, when you launch the Unreal editor, open the Task Manager and see in the Unreal Engine sub processes if Unreal Shader Compilers are there. If they are, then definitely the Engine is compiling the shaders that it needs to start the first time. In that case, I say it again, just be patient.
I waited more than hour, on very good CPU… And as i said, CPU load at 100% will be only for 10-20 seconds, after only base process do some “work”, which is endless
They were complaining of this (with no solution) since at least 4.12 !!! I installed 4.21.1 I ran it and created a new project, then as it is opening the new project,… Stuck at 45% since yesterday about noon… about 21 hours (so far…) 8th Gen core i7, 16GB ram,. TX 1080 Ti Founder edition, etc. (and all Mega fast M.2 SSD WD Black drives!
I think someone found the answer about ten years ago, “SWITCH TO UNITY”,
Now that would be, SWITCH To LUMBERJACK!!
That seems to be the only answer I can find,… :~)
What a joke, working in Unreal, is like living in a NIGHTMARE but I can’t wake up! (or start a new project LOL LOL
LOL LOL LOL TEARING MY #^#%&() HAIR OUT!
HATE UNREAL
HATE EPIC LOLOL LOL HHAHAH
JOKE OF THE COSMOS that they are named: ‘Epic’ … Epic fail…