That Hide option is not to hide the feature, it is to hide the surface body created by the feature. There is not always a 1 to 1 match of bodies to features; one feature can create multiple bodies and multiple features can contribute to a single body. Therefore, there is no way for us consistently indicate on feature icons a hidden/shown state (the state would constantly be changing based on features merging and diverging to result in different bodies).
If you look further up the tree, there is a surface bodies folder. Inside that folder are listed all of the current bodies and that is where the hidden or visible state of each body is indicated with the icon change. If you have multiple solid bodies, then you will see a folder for solid bodies too.
I hope this helps,
Thanks for your response!
OK I shall keep the Surfaces folder at the top uncollapsed and Hide them from there.
Thanks for your help!
With kind regards,