Grid Snap not snapping to grid points

I decided to design my own sheet formats for drawings, complete with a shaded DXF logo to avoid giant file sizes and pixelation, and now I'm trying to use the grid to align things between different sheets.

I have a two sheet template; each sheet has a different sheet format. On one sheet, when I turn on snap to grid, it snaps as expected---as I drag a line's endpoint, it snaps to the intersection of two minor grid lines.

On the other sheet, the snap point is not on the intersection of the grid lines. Perhaps by coincidence, it is snapping to where the endpoint of a line used to be. Makes no sense. I've tried restarting, turning the grid on/off, etc., and nothing will make the point snap to the intersection of the grid lines. I've even turned on the rulers and verified that zero, zero is on the corner of a page.

Anyone seen this?

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