it seems that Some fonts like Asian or Complex script are lost in target file (character properties tag) after a simple processing of input file:
// Load diagram
Diagram diagram = new Diagram(dataDir + "Font.vsdx");
// Save diagram
diagram.Save(dataDir + "Font_Target.vsdx", SaveFileFormat.VSDX);
Font.zip (16.3 KB)
We have tested your source Visio drawing with the latest Hotfix version 17.9.1 of Aspose.Diagram for .NET API, and could not find the difference in fonts. This is the output VSDX drawing: Font_Target17.9.1.zip (14.8 KB). Please download and try the latest Hotfix version: Aspose.Diagram for .NET 17.9.1 and let us know how that goes into your environment.
Please see attached picture for information missing in target file
targetFile.zip (19.8 KB)
The complex scripts font drop down is not visible in Microsoft Visio 2013 and 2016. Kindly let us know in which Microsoft Visio application you are viewing font tab. However, we managed to replicate the problem of empty Asian text drop box Snapshot.png (7.7 KB). It has been logged under the ticket ID DIAGRAMNET-51373 in our bug tracking system. We have linked your post to this ticket and will keep you informed regarding any available updates.
The linked ticket ID DIAGRAMNET-51373 has been fixed. Please download and try the new version 17.10 of Aspose.Diagram for .NET API.