Thanks.
I don't know what's up with Office - how that relates to the problem - is it like the test profile?
I'm thinking the original MSFT profile & the test profile each have a separate set of OneDrive offline folders linking to the same OneDrive site. I doubt they each always try to sync - but each does so only when respectively signed in. Then, the one signed in gets updated for what the other did.
(a) When signed in to the test account - can he even see the Status icons of the original profile?
(b) If so, I guess maybe they could have double-arrows, if signed out before syncing was completed.
But the problem existed in his original profile before the test profile (which works) existed. So - I'm still really confused (unless that Office situation does it).
I do want to know whether the folder sizes match precisely when signed in to one then the other.