The very strange PowerApps parser strikes again. After checking and double checking my syntax and still getting the RecordNotFound error, I just saved/published/closed the file. When I reopened, all is fine. I suspect that it got a bad record early in the construction process and didn't clear that error until I closed and reloaded.
Now the only remaining question is where the documentation between original UserProfile and UserProfileV2 is? Same for the DirectReportsV2, MyProfileV2, SearchUserV2, UserPhotoV2 methods. I am curious as to what has changed and is the old one just in there to protect backward compatibility?
"mobilePhone: " & Office365Users.UserProfileV2(txtInfoAbout.Text).mobilePhone and
"mobilePhone: " & Office365Users.UserProfile(txtInfoAbout.Text).mobilePhone