I don't own 24c, but I have noticed a bug in Universal Control App (I'm on Win10) that causes the option to change the block size to vanish, which is where you change the block size. You can open it from your taskbar or from inside S1 (options > audio setup > audio device > control panel) I've found that sometimes I have to reboot in order for the options, including block size, to show up in the Universal Control App.