Protecting sheets removes the all cell comments - LibreOffice Calc - file format xlsx

LibreOffice versions: 5.1,
OS: Elementary OS 0.4.1 x64 (a derivation of Ubuntu 16.04.2)
Kernel: 4.4.0-131-generic

When I protect a sheet, the all comments I wrote on cells will be removed.

The steps to re-experience the issue:

  1. open a blank sheet
  2. right clik on any cell and select the command of “insert comment”
  3. write down some text
  4. right clik on the current sheet name from the bottom of the sheet
  5. select the command of “protect sheet”
  6. press on “OK” button on the dialog window (so, give a blank password)
  7. save the current file with “*.xlsx” (MS Excel 2007-2019) file extension and close Calc application
  8. re-open the file

Now it can be seen that there is no any comment on any cell, unfortunately…

Mike Kaganski has pointed out to file format. My file extension was xlsx. I’hve corrected the steps above.

Works fine here with Version: (x64)
Build ID: efb621ed25068d70781dc026f7e9c5187a4decd1
CPU threads: 12; OS: Windows 10.0; UI render: GL;
Locale: ru-RU (ru_RU); Calc: CL

I remove the current LibreOffice and downloaded v6.1.0.3 and tested again. The issue continueing on Elementary OS. I tried on 2 different computer with different versions but unfortunately…

Maybe the short “save the current file” hides a secret, like “save to format FOO”?

Yes! I have completely forgotten that my file extension is “xlsx”. I have to edit the question…

Yes - this way I reproduce; please file a bug report.

It has been reported: