You are unable to fill a blueprint with slabs in it, unless by using the `ADD ALL` button.
Steps to reproduce:
# Spawn a shipcore
# Place slabs on that shipcore as well as other types of blocks if you'd like
# Blueprint it
# Buy that blueprint and attempt to fill it (without using the `ADD ALL` button)
# Notice you can't fill in the slabs
Example:
{F3993}