In one of the support ticket you sent me Aspose.Cells DLL version 17.10.3.0. https://forum.aspose.com/t/ds-21625-headlines-font-is-changing/165927/4
When I using it with my system, I get the next error compilation:
CS1061 C# does not contain a definition for ‘Select’ and no extension method ‘Select’ accepting a first argument of type could be found (are you missing a using directive or an assembly reference?)
There are always two dlls. One is compiled in .NET 4.0 (you should use this one because Advance Features of C# and Visual Studio are support by .NET 4.0 dll) and other is compiled with .NET 2.0.
But if you are using .NET 3.5, then you will always have to wait for 1-month. Because .NET 3.5 dll is released only in Official Releases.
The Official Releases contains dlls in these folders according to your .NET Framework.