Why don't my F# lambdas use ligatures?

[rlundy]

Using Fira Code with Visual Studio 2019 in an F# project, my lambda expressions don't use the Fira Code ligatures. For example:

Fira Code is enabled (replacing |> with the triangles), but the -> doesn't get the arrow ligature, even though this ligature exists and works in e.g. Java lambdas (albeit this is in VS Code):

Any ideas why?

[tonsky]

Yes https://github.com/tonsky/FiraCode/wiki#some-ligatures-work-while-some-dont