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Did you happen to use one of the wp.org child theme creator plugins before you did the peocess above to create the child theme?

No I never tried anything else as I only used Custom CSS and had no issues up to this point.

One thing you might try. Reactivate the parent theme, copy all the css out of the theme custom css option, save it somewhere, delete all the css in the custom css option, save, reactivate the child theme, paste the css into the child theme style css file using the Editor, save, and see if that makes any difference. In any case this is a good thing to do since then you won’t have to worry about saving or losing your custom css if you upgrade the parent theme.

Nope even with no CSS edits in either it makes no difference.

OK, I should retract what I said earlier. I thought the menus would come across and, in the testing I performed, they did, so not sure what happened there. However, even though the sidebars should still exist (including any custom sidebars) in the child theme, the widgets in the sidebars appear to be theme specific. So, when you activate the child theme, the sidebars would be empty, which is what you experienced. If you added widgets to the sidebars in your original (now parent) theme, you need to recreate them in the child theme. My apologies for not doing more testing earlier today.

No apologies necessary you are an amazing resource here on the forums! Thanks for testing I really do appreciate it!