I have many Unions in some of my places and I use the Studio > Settings > Physics > ShowDecompositionGeometry to tell me how the Unions are actually shaped.
So when I click on the checkbox only a few of the Parts show up as multi-coloured triangles and squares to denote the Unions actual shape. If I hit F6 and test then they all show up.
I realize that there is a warning that Studio should be shut down and restarted to make it work correctly, but it seems very strange that it will pick up most Unions on the first time you click it, but not all of them.
Having them show up in Neon can be a real pain too. Having a bunch of Neon Parts ‘together’ (as a Union is displayed) is just hard on the eyes and doesn’t serve a purpose other than to remind me it’s a Union, but I know it’s a Union! I made it, it appears as multi-coloured triangles and squares and it shows up in my Explorer window as ‘Union’. Could they just show up as SmoothPlastic so we can see them a little easier and they don’t glow all over the Parts we are trying to match them up with?