A combo that has only the top half solid and is of combo type "Hookshot Only" or "Ladder or Hookshot", it won't allow the Hookshot to be fired when Link stands directly below it.
It works fine if Link is not directly below the solid part of the combo:

But it doesn't work when hugging it:

Is this in all beta versions or what?
Well, yeah. I didn't put [742] at the beginning of the title since this bug has existed since the Hookshot was added to ZC. The bug in which the Hookshot wouldn't fire when Link stood under a fully solid Hookshot combo has been fixed, but this is another variation of it that is not fixed.