The gridlines that align with the content (master/placed drawing) are a hint that somehow the rotated grid was turned on. At the bottom left of your screen, you can see this is the case by the rotated grid selection button. Also, above that - lower left of the layout window, you can see two black arrows for the x/y axes ... and can see that the y axis is currently rotated to be to the right and down. I don't see why this would affect existing layouts, only newly placed stuff.
Switch by to orthogonal grid to see if it helps. Check your master layout and see what grid setting is in use there. Verify that the desired master layout is associated with each layout - change the display of your layoutbook to group by master. It doesn't look like the currently selected master is big enough for your sheet content, but maybe that's the way it was before.
One of the forum moderators
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