Scale hidden objects within a group.
Objects in a group that are hidden should scale along with the rest of the group, like they do in Photoshop. (Or it should at least be an option alongside the "scale strokes & effects" option.)
It makes absolutely no sense for them to be left behind.
Construction lines & other elements that form part of a build (but are usually hidden) cannot always be grouped separately in order to make their management easier. Sometimes there are many, many elements interspersed amongst a build that need to remain there but to have them switched on can make scaling & positioning something like a logo incredibly difficult & time consuming.
There are workarounds, of course, but that's not a solution, it's a temporary fix. Side-step the mess & you've worked around it but look behind you & the mess is still there, ready for the next person to step in.

The behavior differs on how the objects get hidden and selected. Jump into comments for the explanation if something like this happens for you.
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del commented
As far as I can tell, it was my mistake. I was selecting the visible objects & scaling, which left the hidden objects behind.
When I de-selected everything & selected the group node (actually the layer node in this case but I'm sure it works the same with the group node) everything scaled as expeced.
Apologies for wasting everyone's time.
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@del, they do when I check the behavior. I tried scaling a group with a hidden object with just bounding box, with dedicated Scale tool, transform it using Transform and other panels... in all cases the hidden object gets affected.
But there’s an important aspect you should know when trying, and Layers panel is there to help you.
Here’s a simple demo.
When you hide a child in Layers, Ai automatically excludes it from your selection — the square selection marker indicates this. So, if you scale the group after this, the red circles gets omitted.
But if you select a group with a hidden object (or click the circular target marker immediately after hiding a child, even though it’s not its intended purpose) — the hidden red object gets included.How does it behave for you?