I just dragged and dropped a 4k .hdr found at HDRIHaven with a clear sky and bright sun, and I get a weird black hole in the texture asset freshly created, where the sun should be.
There is no artifact in 4.27.2 with the same import process, same compression settings (HDR - RGB, no sRGB) and so on.
Changing the compression Settings from HDR (RGB, no sRGB) to anything else causes the artifact to disappear.
This weird artifact appears with many hdrs, it’s not only with this one. But you can grab the .hdr here.
Had same issue and shadow artifacts that being casted from the HDRI. Found that its a problem that comes from HDRIheaven HDRI’s , took one from different source and it got none of those issues.
Not saying that HDRIheaven is the reason for the problem because they had none in UE4 but it is a solution for now…
I guess it’s because HDRIHaven HDRI’s are true .hdr with full range values. (Some HDRI’s are simply clamped)
Maybe there are some crazy values in the sun position.