23andMe split view discrepancy

[KATM]

I was using the Split View option in Ancestry Composition at 23andMe. I have my results and my father's. My mother never took a test and is deceased.

My father's results show different percentages for different population groups when comparing his results for him alone, to that of his contribution ("From Father") in Split View with me. For example, he has no Italian or Balkan in his own results, but those populations show for him under Split View.

Is there a simple reason for this? I can post the lists of percentages.

Since I don't have results for my mother, I suspect there is some incorrect assignment under his contribution for what would be her possible results (my "From Mother" in split view does show Italian and Balkan, for example. Southern European/Balkan is in her ancestry, but not known to be in my father's).

[AlisonT]

Yes, the same thing happens with my mother and her father. He's contributing .1% Sub-Saharan ancestry and .1% Sardinian in split view, both of which disappear when just viewing his own ancestry composition. My mother had a tiny .something % North African before her split view was computed, which then changed to .2% Sub-Saharan.

[Brunetmj]

Another way to express this issue is phased data versus actual data.
Phasing is the name given to the process of comparing a parents genome to that of one of the children and extracting information for the missing parent.
I am sure there are differences but I could only speculate. So will leave this to someone more knowledgable than I.