The problem lies in the account itself, but rather in the date of its creation. Everyone who created an account before 2017 has any problems with displaying friends in the list or not displaying them at all. I quote the decision uv.sopilka1 :


I scanned the QR codes of the local people - now I really see everyone. Arsen is really right - the old acca do not quite correctly work with friends who have new (fresh) acca. Now everything is displayed, although I have firmware and Mifit from lolex ("Russian" custom from the Chinese version)

That All: There is a fly in the ointment for those who want to do the same. (It is necessary for those who, instead of statistics from friends, have only zeros displayed / disappear friends, etc. - the rest do not need to do this!)
So far, there is no solution, how to transfer statistics from the old Mifit account to the new
Attention, before starting a new account, you must untie your bracelet from the old one! Otherwise, not only will you lose your statistics, but you will not be able to link your bracelet with a new account!]