Blocks not working properly

Greetings all. I hope I’ve finally navigated to the right place.

I’m having two semi-related issues with Blocks that are really cutting into the productivity for my team and myself on our site.

1) When writing posts on our site we use with OVERWHELMING frequency the Paragraph, Heading, Custom HTML, YouTube, and Image blocks.

Yet, despite having what seems to be the appropriate box ticked (POST screen/ PREFERENCES/ Show most used blocks -Places the most frequent blocks in the block library) the “Most Used Blocks” sub-window that pops up when ticking the + consistently shows the same six blocks, three of which we simply never use: Embed, Twitter, and WordPress (see attached image).

Although we do A LOT of embedding, we prefer to use the Custom HTML block over the Embed block because the latter rarely works with what we are embedding, so using the Embed block is not an option.

Is there another method I should be using to ensure that the appropriate “most used” blocks that we actually use populate in that window?

Furthermore, using the Block Manager, I encounter the following issues:

1a) Attempting to disable the Embed block also completely removes the YouTube option, making this a non starter.

1b) There seems to be no means to disable the Twitter or WordPress blocks to force them not to populate.

2) Pursuant to the above, a few months ago (maybe? time is strange nowadays) an update to WordPress changed the amount of “Most Used” blocks that populated in the sub-window from, I believe, 8 or 9 down to 6. Before this change those couple of extra blocks truly covered EVERYTHING we ever use. Is there a way to return to more blocks, or alter the behavior of the sub-window to show more “Most Used” blocks?