I have a spreadsheet with 23 tabs on which I’ve placed many cut-and-pasted images, and also added rectangles as drawing elements. The images and some rectangles were carefully aligned to have their top-left corners coincident with the top-left corners of a cell. Other rectangles aren’t so aligned, but are carefully placed relative to other rectangles. But whenever I close the file (after saving it) and reopen it, the drawing elements, both images and rectangles, have moved slightly from where I put them, and the discrepancy is increasing with each close and reopen. On some tabs, all the drawing elements are now about 8mm to the right and 2.5 mm above where they ought to be. I hoped that anchoring the elements to the cell rather than the page might help, but it didn’t. I can move the elements back to where they ought to be, but they just start drifting again.
Doing some testing, it appears that every time I close and reopen the spreadsheet, the graphical images move 0.75 mm to the right, and 0.25 mm up. (After 4 saves, they had moved 3 mm to the right and 1 mm up)