Hi @dan,
Thanks for your reply, I have downgraded the packages to the versions used in the example you provided, but that made no difference. But thanks to your comment I was checking the ClientSecret while debuggen and it turned out that some Windows environment variable also was named SampleApp__ClientSecret and thus was overwriting the value I provided in my appsettings.json. After setting the ClientSecret in the immediate window in Visual Studio, I was able to redirect after logging in. Now, I only have to figure out which application is setting the SampleApp__ClientSecret environment variable.