Please read the previous posts, it’s about the same topic. On the same workbook I have the same issue (merged cells which are displayed unmerged). I don’t think it’s necessary to send you the sample project again.
Please execute it, go to I. 100 worksheet, and stay focused on the “Actifs détaillés” cell which is a merged cells (B8 -> N8) . After scrolling down and then scrolling up a couple of time, this cell look unmerged as you can see on my previous attached screen shot.