There should be a connector on the top of the bottom. It looks like only the stop and delete this clone blocks are allowed to go there.
That's not a bug! There's no dent in the bottom of C-slots even without text below them. The dent you want is in Scratch 3.0 but not in any earlier version, and with respect to the visual presentation of blocks and scripts we follow the 1.4 style. :~)
oh. i like how snap looks but i thought that was a little weird (and strange how I never noticed that before).