From the little i know about when do you use 3ds max to make VFX for games is: you render out a particle simulation, then you use after effects to make the sprites out of the render and then you export them into UE4 to start making your effects. Some of them will only need to use UE, others just Photoshop+UE4.
I don't know how to answer that. I believe it has something to do with normals. It's not the green channel needing flipped if that's what you mean. It looks fine in 3ds Max and Marmoset, but not UE4. I have confirmation that it shows the error in another engine. I threw it into a UE4 marketplace scene. It's fine until I…
Do you have a link to such footage + the specs of said laptop ? Otherwise any comparaison is quite litterally pointless really. Overall UE5 isn't as magical as one may be led to believe. Even the editor alone is slower than UE4.
There is no date or period about the release of the UE4 announced officially. And as far I know there is also no "unofficial" date either on Teh Internet.