Please try using the newline metacharacter (\n) as follows. In case you still do not get the required results, please share your complete code along with supporting documents for further analysis.
First of all, please accept my apology for not noticing that you are using VB.NET as your coding language. You are correct, the string \n printed as it is in the title because VB.NET is not able to recognize it as a metacharacter. Please use the following equivalent statement for your requirement. I have also attached the VB module here in an archive that I used for my testing along with its result.
VB.NET
chart.Title.Text = "One line " & vbNewLine & “Another Line”
Inserting vbCrLf as new line feed is working equally correct on my side, however, I prefer to use vbNewLine instead of vbCrLf as it is a more descriptive variable that does the same thing.
Anyway, please create a zip archive of your complete project (including the dependencies) and post here for further investigation.
Could you please try the latest version: Aspose.Cells
for .NET v8.6.0.4 because it is working fine. I have tested it with the following sample code and attached the source and output excel file for a reference.