I am not able to move the app block freely under the desired section on newer versions of the Horizon theme. It is hard to explain, so I recorded a video to demonstrate what I mean.
I also tested this with other apps, and none of the blocks can be moved.
Theme version: 3.2.1
I think it is not possible to drop a block into another parent, the drag works only to change the position between the siblings. It seems to be true in Dawn theme as well.
Thanks @Dmitri_Pavlutin Interesting, I just tried with Dawn, and the same thing is happening. I am almost sure it wasn’t like this before 
But anyway, this would be a huge improvement for the UX.