Problems using 'Rendered entity - Block' in header/footer

I'm surprised that neither of these issues, especially the second which is a definite bug, have been addressed in all this time.

Just to confirm that using the global block area provided by the views_block_area → contributed module worked for me too.

For what it's worth, I found this option: "Rendered entity - Block" did not render the block in the view header or footer, but this option: "Rendered entity - Content block" did render the block. Key word being "Content" I guess. I would agree that the difference between these are not evident.

I figured out a bit more of this. If I create a block plugin with an ID of 'my_custom_block'
and I try to use that ID in the header of my View, it is completely missing from the output.

However if I place the block in a region using the Block Layout admin UI, the block instance is given an ID that looks like 'my_theme_name_mycustomblock' (notice all the underscores removed from my block id) and if I use that ID in the "Rendered entity - Block"
It will display.

I can work around getting that on a single site, but I want the View and Block to ship with contrib module and I can not predict the name of the theme that would be used where to fake place this block so it does not show twice.

This is a core bug that really needs to be solved.