Created attachment 138248 [details]
Example file made with Excel 2013

If we create a 3D Column chart in Microsoft Excel 2013/2016 the default setting of label rotation will be horizontal. Even if the labels are too long to fit, the Microsoft Excel automatically rotate the labels in the most optimal way (vertical or -45°). When we open the spreadsheet in LibreOffice the X category axis label will be vertical (which is the same as the MSO Excel default rotation setting), even if it doesn’t fit.

Steps to reproduce:
1. Create a new spreadsheet in Excel 2013.
2. Create a simple 3D Column chart.
3. The X category Axis labels should be properly long strings, so the MSO Excel will rotate the labels automatically. Or you can resize the chart area and the MSO Excel will automatically rotate the labels.
4. Click right on the diagram, and select the 3-D rotation.
5. Remove the mark from the “Right Angle Axis”.
5. Save the file and close Excel.
6. Open the same file with LibreOffice Calc.

Actual results:
The chart label isn't rotated anymore, because the default rotation setting is horizontal and the “Right Angle Axis” option was not checked.

Expected results:
The chart label should stay rotated.

***************************************
In LibreOfficeDev Calc
Version: 6.0.0.0.beta1+
Build ID: 29228e83df009cf76ac819ed024527be1092f065
CPU threads: 4; OS: Windows 6.1; UI render: default; 
TinderBox: Win-x86@42, Branch:libreoffice-6-0, Time: 2017-12-04_23:15:34
Locale: hu-HU (hu_HU); Calc: group threaded

7. Open the original file with LibreOfficeDev Calc save as the file in xlsx.
8. Reload the spreadsheet.

Actual results:
The X axis label is disappeared.

Expected results:
The x axis label should not be disappeared.