OS version: Windows 10 64
App version: 8.0.1.31 (x64 msi)
Downloaded from: ONLYOFFICE website
To repeat: Open a new spreadsheet, create a comment in cell A1, create a comment (different from A1) in cell B4, copy cell A1, and finally paste special, choosing only “Comments,” into cell B4.
B4’s comment remains unchanged.
New users can’t upload files, so I’m sorry to put the burden on the reader.