Don’t think it makes a difference with this but can you change your Services to return a DTOs or a Reference Type. For bool responses you could return an
EmptyResponse when it succeeds and throw an error if it fails, or if you don’t want to return a DTO you can return a string, e.g. “true”.
Do you have .NET 5 installed? as it’s required by the dotnet tools. Otherwise I can’t see what’s interfering with ServiceStack Responses from here so would need a small minimal repo I can run locally to repro the issue to be able to investigate further.