@Nat, there is a bug (at least in Firefox) and this game is unsolvable. Like SkyCharger mentioned, once you activate the sundial, the graphic does not change and therefore you cannot interact with that puzzle or get any farther in the game. Perhaps we have to play in Chrome...
I played in Firefox with no such issue. Could you describe in a little more detail? Did the pointer thing not appear at all in the detail window? Was it only after backing out and zooming in again? Otherwise, how did you know that what you did was meant to activate it at all? (And in future I'd appreciate if you replied directly to the post so that I find out that you said something to me.)
Edit: Went back to test and I did get the sundial detail issue this time. After the sundial is activated, the part that sticks up will always be visible in the general view, but neither it nor its shadow are visible at all in the detail view. I still have to test how exactly this is clue-proofed, but since I knew that the shadow is meant to point to 12, getting the bug didn't keep me from progressing in the game. Currently editing all my comments to reflect this.
Edit 2: ...oh. More testing shows that the time puzzle isn't clue-proofed at ALL. So knowing those time codes allows you to skip half the game. Still can't figure out what causes the bug...
Edit 3: I tried to emulate the way I first played the game, looking at every detail window before I did anything and visiting random unrelated spots in between steps, including the sundial detail several times. I didn't get the bug, and not only that, but I found an actual existing magnet side view without the magnet. So either the game got updated, or the problem is caused by doing things too quickly.
No, I'm pretty sure they didn't update it lol, I just thought that because the magnet disappeared and I was shocked. I think it's just a conditional code error that only pops up some of the time. Like I said, if you click around literally everywhere and take forever to get to that point, it seems to display it fine, and either way, if you know what it's supposed to say, you can enter the times code to finish the game at any time.
EDIT: I came back to test just a little more because of your reply, and I figured out EXACTLY what causes both the magnet and sundial problems. If you've visited those detail screens before they should be altered, they will be altered, but if you see them for the first time after triggering the alteration, they remain unaltered and you'll NEVER see the altered versions.
TLDR: Just click on the sundial and look at the face before you solve the puzzle to make the arm come up. Should solve the problem!