I have a subscription to GCN+, and I could not watch live either. Note the following from the schedule list for USA:
27 February 2021: Omloop het Nieuwsblad (Highlights)
I hope we still get to watch at least the replay. (Which also doesn't currently load for me.)
During the replay broadcast for the last stage of the UAE tour, the announcers did mention Omloop Live would not be available in North America.