I have use Aspose.Diagram to convert visio .vsd to .vsdx format. I found one document which looks different after convertion:
screen.png (71.4 KB)
Test project:
VisioTester.zip (49.6 KB)
Thanks
Thanks for posting your inquiry.
We have created an issue under the ticket ID DIAGRAMNET-51783 in our issue tracking system. We will further look into its details and keep you posted with the status of its resolution. Please be patient and spare us little time.
We are sorry for the inconvenience.
We investigated the earlier logged issue and found that it would not be fixed, because MS Visio handles the both sides space of centered line in .vsd and .vsdx differently. The spaces in .vsdx file are ignored, but the spaces in .vsd are not. We used MS Visio to save that .vsd file as .vsdx file and then reopened the .vsdx Visio saved. We found it was displayed as the same as we generated. So this is not a bug.