If you fetch a block manually in a template with
"$block = fetch( 'ezflow', 'block', hash( 'block_id', <BLOCK_ID>) )"

and than afterwards using
"block_view_gui block=$block"

always the default "block/view/view.tpl" is used. No override rules are used.

If you look into the block object inside a block template, you can see that this block object differs from one that you have manually fetched.