Well, you - and every normal user, including me - rightly assume so, because it was like this since the beginning of time.
However,I just realised that - due to a thoughtless and completely incomprehensible decision, this is no longer the case. There is nothing about in in a changelog either, but:
In the web version “Unhide All” command un-hides all hidden geometries and objects including nested.
This is unusual, unexpected behaviour, and I don’t see a reasonable explanation for the unannounced change.
So yes, the topic starter screwed up her previous work with one click.
I personally regret this very much. I hope the developers reconsider their decision.
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And I apologize for not understanding the problem and not looking into it more closely earlier. However, the suggestions I made in my #9 comments still stand. 