Codec not found even though IConverter created

Im getting a `CodecNotFoundException` when trying to serialize a generic struct type from an external lib, `OneOf` https://www.nuget.org/packages/OneOf

Here is my `IConverter`

``` cs
namespace Grains.Surrogates;

[GenerateSerializer]
public struct OneOfSurrogate
{
[Id(0)] public GameCardModel? V0;
[Id(1)] public GamePlayerModel? V1;
}

// Implement the IConverter
[RegisterConverter]
public sealed class OneOfSurrogateConverter : IConverter, OneOfSurrogate>
{
public OneOf ConvertFromSurrogate(in OneOfSurrogate surrogate)
=> surrogate.V0 != null
? OneOf.FromT0(surrogate.V0)
: OneOf.FromT1(surrogate.V1!);

public OneOfSurrogate ConvertToSurrogate(in OneOf value)
=> new()
{
V0 = value.IsT0 ? value.AsT0 : null,
V1 = value.IsT1 ? value.AsT1 : null,
};
}

```

And here is the generated orleans code where the error originates
``` cs
_codec0 = OrleansGeneratedCodeHelper.GetService>>(this, codecProvider);

```

The `IConverter` is in the same assembly as the grains and the sdk is installed

```xml

net7.0
enable
enable

























```

I have another surrogate in the code base which works fine for a non generic struct type so im not sure what the issue is here.