I was just trying to change the texture of a light fixture and couldn't see on the preview what I was changing ... it appears that the preview no longer works, and if the items you are trying to change don't have a really specific description then you can't tell what you are changing. This worked fine in 2016, but appears to be broken in 2018.
Running a test on a Ford 150 3D symbol - Changing the colour from Red to Red-Violet I get this is 2016 ...
2017.04.26_11h40m34s_001.png 70.02KB 5 downloads
and this in 2018 ...
2017.04.26_11h41m57s_002.png 68.06KB 2 downloads
It's really difficult to change colours if you can't see what you are changing.
Is it just me, or is it broken?