Using a zero client and am able to authenticate to Horizon, when i'm taken to the windows screen windows behaves as if there is no smart card. At that point I have to log in with username and password.
When I log in I see activclient loads and it sees the smart card fine. If I lock the screen I can then log back in with a smart card.
Using horizon 8.3, activcliient 7.1, win10 20h2, teradici 6.1 and 21.