Can a ultrasound sometimes not show a mass

hello,

This last week I went in to have my mammogram done and I had been feeling a lump in my left breast. So they marked where they could feel it and sure enough on the mammogram there it was a mass right behind my nipple and also microcalcifications cluster together and attached to the mass. Radiologist said ACR BIRADS Category 4: Suspicious; ACR BIRADS Category 4: Suspicious; malignancy. And they did an ultrasound which nothing showed on it but the Tech that was doing the ultrasound literally barely even pushed down on the paddle and only took like 2 minutes to do which I thought was weird. I’ve had ultrasounds on my right breast and it hurt because they would push down hard and of course take longer than 2 minutes. My question is has anyone have a mass show up on mammogram and not ultrasound. I’m having a Stereotactic biopsy this Friday.