So confused

I had my 19W5D anatomy scan a little over a week ago & I got a call on Tuesday stating that they found 2 cysts in the brain & 1 in the heart which is a “soft marker” for Down syndrome. I did the genetic testing during my 1st trimester & finished up the second half in the beginning of my second trimester & my genetic testing came back negative for everything INCLUDING Down syndrome. They are now referring me to a maternal fetal specialist & had me do more “thorough” blood work. Has this happened to anyone else ? I can’t even wrap my head around this, especially since my testing came back negative.