Search result does not include resuls from a tag in the block with the tag of the parent block

I place this under bug reports because of the commonly used expected behavior not happening:

Parent block A has #tagA
Child block B (inside block A) has #tagB

for example:

  • This is the first line of the parent block with #tagA
    * This is the first line of the child block with #tagB

I like to search for all blocks with #tagB which are part of blocks with #tagA.
My commons sense says me that block B inherits the tags from Block A since it is part of block A.
Therefore, I search for:
#tagA #tagB

However, that gives no result at all, nothing.

Why is this not implemented yet, or is this a known bug?