Related info: https://stackoverflow.com/questions/51559133/poi-3-17-creating-cell-comments-in-a-cloned-sheet-creates-inconsistent-xlsx How to reproduce: - Source sheet contains comments - Use cloneSheet to copy - Create new comment in new sheet - Save - Open file with Excel Result: Excel wants to recover the excel. Afterwards the comments from the original sheet are gone. Workaround stated in url reference is working.
I suspect it would be better to rewrite cloneSheet to use the XSSF APIs to create a new sheet and to copy the data and comments from the source sheet instead of trying to work at the low-level CT generated class level and cloning all the relationships.
A related problem regarding cloneSheet with comments is that removing the comment from the cloned sheet produces a NullPointerException in XSSFCell.java:1087 (POI 4.1.1) Attached a sample to reproduce.
Created attachment 36997 [details] Test case