The slot in the Research scanner where you take out the Research Blueprint only shows the item it contains when it contained that item the moment the GUI was opened.

Even if you don't see the item in the slot, you can take it out.

Also, perhaps it has always been like this, but currently you don't need to press the Scan button for the item to appear in the research blueprint slot.

As long as you have the right item in the top left and the right aspects selected, you can take the Blueprint out (even though you might not see the blueprint in the slot).

In the latest version, the Scan button updates the Research slot visual again.