First guess out of the box is that maybe the wheel simply isn't tight enough, or worse, very unevenly tensioned. You can gauge the evenness of tension by spinning the wheel with a thumbnail pinging the spokes. The tones should be uniform, except hat the right nd left sides won't match. If whn you spin the wheel you hear ping, ping, pong, ping ping, pong, pung... you have a poorly built wheel.

There's also the (rare) possibility that the right and left flanges aren't phased properly, but I'd need a photo shot straight across parallel to the axle.