Objects not pinned on a page

Hi guys,

I'm having an issue with adjusting page position/ sizes and not understanding where the problem comes from. I believe it's a parameter I have to tick/ untick but can't find it anywhere.

The issue :
- Using the Page Tool (Shift +P)

- Screen 0. Original position

- I select the Page tool and move the page to the right. The page moves, but the blue rectangle stays where it is, not going along with the page wherever I go.
- This is particularly not good when dealing with book covers, ie, when I stack 3 pages (C4+Spine+C1)

The thing is, it worked fine before. Objects were somehow anchored to the page. Not anymore.

I've thought about the settings of dimensioning the pages via page/ spread, alignement, auto adjust content etc, but nothing works. It's like objects are now pinned to the pasteboard rather the pages.

Any idea guys ?