If the student is actually withdrawn, there should be no data included on the student. If they are current students, there should be transcript data which is where GPA draws from. Check to be sure that the student is actually missing semester 1 transcript data.
For high school students who have no transcript data (i.e. situations like a student entering with no transcripts available right away in the school year), make a manual entry on the student’s transcript record as class title “Waiting on Transcripts” and credits 0 and P as the grade (check mark the box to calculate). Once saved to the transcript record, the Data Rollup system sees a GPA there and the error will not show up. The registrar will need to delete this transcript record when actual transcript records are entered so that the calculations are accurate.