No, the sound of the chord shouldn't come through when you do the chunk. There are a few things that you could do to help.
- Relax your strumming finger(s). Don't keep the fingers you use to strum too stiff when you do the strum part of the chunk.
- Increase your angle of attack. Instead of bringing your hand straight down like you would to strum, bring your hand down at an angle toward the face of the ukulele, almost as if you were trying to slap the sound hole with the nails of your curled strumming fingers and the outside edge of your thumb.
- Lift up on the chord, slightly. With your left hand, release the chord so that your fingers are just resting on the strings instead of holding them down hard when you strum the chunk.
hopefully one or all of these helps you out. Shooots.