Created attachment 31547 [details] Java Class file to run the bug and Excel file result. Creating some cells (100 lines of 20 cells), in a new sheet, in a new Excel file, adding a comment in each cell, at least, the comments of the first 976 cells have disappear in the file. I have made a synthetic Java class, which is in the attachment, to present this bug.
There seems to be a hardcoded limit of 1024 comments currently which throws away older comments when more are added, see bug 56380, this one is likely a duplicate of that one. *** This bug has been marked as a duplicate of bug 56380 ***