By right clicking on a ship core in astronaut mode, you normally get a popup dialogue asking for confirmation to remove this last block.
That's not happening anymore in a certain situation, instead, you get a "cannot be hit by this beam."
As soon as you build a block, it works fine again. (spawn in a new ship core to remove it)
To get it back into a broken state, you have to try and place down a block in build mode when you have an empty slot selected.
You'll get the "no element to build" info message and your right click won't be able to remove ship cores once again.
Probably caused by the beam optimizations?