Hi,
When opening attached document in “Calc” I’m not notified about any possible issues, but the last sheet is missing.
When opening in “Excel” I’m notified that there ares some issues - and the last sheet which has a " Ø / ø" symbol in the name is not shown.
Opening in “Numbers” works correctly imho
Analysis (1).xlsx (8.5 KB)
Anything in Excel native formats (XLSX) that shows errors in Excel, by definition, should be considered broken (until explicitly proven to be an Excel bug). So - no, I would not consider any third-party application doing things differently compared to Excel on Excel’s files as “correct”.
(Interesting to know what has generated such a document; the metadata tells “Microsoft Excel”, but any third-party generator can write that.)
And what could add CR to the sheets’ names (visible in the file’s xl/workbook.xml)?
And the actual problem there is not Ø, but / slash in the sheet name. Excel, by the way, doesn’t allow to use it in the sheet names. Editing XML to replace / with _ makes both Excel and Calc happy.
Analysis (fixed).xlsx (8.5 KB)
I understand - I was just surprised that Calc didn’t warn me about possible issues - thus I started using the file as there weren’t any issues and I didn’t even realize that something is missing there 
It was exported by some 3rd party app.
I’ve made a test, made some changes in “numbers”, saved the sheet as excel and now I was able to open it with Calc and I also see the missing sheet.
I will contact the app devs to check on it.
Sorry for taking your time and thank you for your prompt reply 
Have a great weekend, Mike!
You may create a bug report (with this file attached) to show a warning on such a broken file. That would be a reasonable issue.
