This is an odd one, which is why it's Breaking Scratch 2.5 instead of 3. What you need to do is click see inside, then create a custom block, and make it's name just %. Then click "Add a label". Now, try and press ok. After trying and failing, press cancel and try to use some other scratch blocks. Maybe clock the "Motion" tab, maybe scroll up in the blocks, it'll be... odd. Have fun!
