When taking empty and unnamed blueprint book from blueprint library and adding it to toolbar, then it will create a blueprint book "blueprint" there.
It will not put said blueprint book there, instead pressing on this slot in toolbar will create new blueprint book every time when the hand is empty.
Empty blueprint book
Empty blueprint book on toolbar
[0.17.7] Empty blueprint book acts wierd on toolbar
Re: [0.17.7] Empty blueprint book acts wierd on toolbar
I can replicate the issue. Can you test that it still occurs? It was probably fixed in the more recent releases