@DONTFRICKME omegaverse concept is imaginary to begin with so author is free to imagine n write whatever they want(thats what they did in this manhwa)... it's not common in an omegaverse for betas to sense alpha-omega pheromones.. betas are like normal people.. hence I've seen in some manhwa they were producing pheromone scented perfumes for betas..
Pfp: My Guildmate Next Door