Here's a screenshot to show what confused me:
On my first play I thought it looked like the activator is on the ground floor, because of how it doesn't match with the tile grid up top, so here I am running into a wall and hoping to access the activator. In my brain, I think I am up against the front left side. But it is unaccessible, so I start wondering if actually it's on the top floor, or there's something else I'm not finding somewhere. I'm busy wondering what's going on with the moving platform on the right, and what's up with the blue square, and whether there's any mechanics I'm missing.
Now that I know where the activator really is and understand the design of the tile visuals a bit better, it's obvious in retrospect that I'm actually up against a corner and not the activator. And I know that the blue square is an elevator, which will be activated by the activator. And I know that the moving platform on the right is a red herring. Now, it's obvious that the solution is as simple as going a bit further left and up, and then the puzzle is solved! At least, it's simple now that I know that's what you're supposed to do, and what all the elements on screen do.
I'm sure I would've gotten it eventually, and maybe I don't look so smart in this screenshot... but since I saw I'm not the only one who got stuck here, I thought I'd go into excruciating detail :)
It really is a beautifully smooth and polished game. That I can nitpick on a level design detail as small as this is a testament to how professional the game feels in general.