Weird material editor preview behaviour using fresnel.

I have noticed some weird behaviour in general when zooming using the scrollwheel in the material editor preview. I have created a simple material using the default values which only binds a fresnel node to the base color, but the same happens with more advanced ones. Here the material view when just opening the material:

When I now zoom using the scrollwheel on my mouse it will look like this:

At any moment when i scroll using the right mouse button the material will be fixed and looks like it is supposed to:

The last image is the only correct one, as the base reflect fraction is set low, so it should be black at normals facing the camera and approach one at grazing angles. This bug also lets the thumbnail preview look wrong, as it looks the same as the in the first image.

Another maybe related bug is when you zoom out far using your scrollwheel, then zoom a little using the right mouse button. Now it is no longer possible to zoom back in using the scrollwheel.

I have tested this in 4.8.1 and also the latest master branch and in the engine itself the material does look correct.

Hey Mazk,

I have re created this issue in 4.8.1. I have put in a ticket for this issue to be reviewed. Thank you for reporting this. The ticket number is UE - 18327

Thanks again,