Nipt Twins Y chromosome concern

Currently 17 weeks pregnant with fraternal twins did the nipt test at 12 weeks and recieved an incomplete result. Low risk for trisomy 21,18 & 13 but test was unable to report fetal sex : The y chromosome could not be confirmed therefore fetal sex could not be reported, this could be a normal variation in DNA patterns but an abnormality involving the y chromosome can not be excluded” My doctor has referred me to a genetic councillor who has suggested an amniocentesis 🙁. Has anyone received a similar result?