My DD's team did this all the time, both on infield singles and on walks. They were usually playing showcase under USA/ASA rules. Her coaches were college coaches, so apparently they and they umps know why is wasn't a violation of the look back rule.
Maybe the coaches didn't educate themselves that there is a difference between and NCAA and USA/ASA on this. Under USA/ASA, it is definitely a violation of the LBR. The umps SHOULD know this.