First Cousin Once Removed - Ancestry Result Discrepancy

Hi everyone!

This is more an interesting observation. My first cousin once removed (child of my mother's first cousin, if you get mixed up with all the terms) and I are matching on Ancestry as relatives. This, of course, makes sense - what is interesting to me is that our shared Scottish ancestry (through our mutual great-grandparents) - is completely missing for my cousin.

My results show roughly 20% Scottish ancestry, which is fully from my maternal grandmother (sister to his grandfather). His results, however, show 0% Scottish ancestry.

I'd almost start to imagine conspiracy theories, but we are both matching more distant cousins on my grandmother's paternal line, who I know through thrulines and their public trees branched off from us from a separate sibling born to one pair of fully Scottish parents who immigrated to the US (in both of our cases, our g-g-g grandparents - so five generations back). The same happened with another Scottish pair on the maternal line - so clearly the DNA is there, but is not listed at all in his results as Scottish.

Interesting that even though none of my other recent ancestors are Scottish or of that heritage, my DNA still selected roughly 20% (which is the current estimate) from my grandmother (who had recent English and French ancestry as well), and yet his (as of today's algorithm) seems to have been fully selected out (despite pinging mutual DNA matches with mutual Scottish ancestors).

Of course this could change with future updates, but he does also have the Y-DNA line all the way back to Northern Scotland, and a very Scottish last name. It almost seems like an error or glitch, if not a unique occurrence of the randomness of DNA selection alongside a developing algorithm and database.

If any of you have thoughts or alternative explanations, I'd be interested to hear!