As I understand it, results on Zwiftpower can take awhile to show up. Since we are not affiliated with them, unfortunately I’m not certain what the case may be. But I suggest you check again in. It looks like you wrote this post on the same day as the race you took part in, but Zwiftpower states, “Results will be provided within 24 hours of race finish. You can check preliminary positions by using the LIVE tab in top right corner.”
If you are registered with ZwiftPower, then I would recommend checking out their forums, as you might find more specific information about specific races there.