If you have merged cells A1:A5, and then delete column 3, the merged cell doesnt recognize that the merged column count should have changed. Meaning, the formatting continues to the new A5 (which was previously A6) - and whatever formatting was in A6 gets overwritten (or hidden).
Similarly, when you have cells A3:A5 merged, and you delete column 1, the merged cells are still A3:A5 rather than A2:A4. The data and formatting flows with the columns on the delete, but the Merge reference does not.
Comments: Please try the latest version of ClosedXML (v0.87.1 at this stage). If you still experience the issue, log it on the new GitHub page.
Similarly, when you have cells A3:A5 merged, and you delete column 1, the merged cells are still A3:A5 rather than A2:A4. The data and formatting flows with the columns on the delete, but the Merge reference does not.
Comments: Please try the latest version of ClosedXML (v0.87.1 at this stage). If you still experience the issue, log it on the new GitHub page.