Phone language: Russian
Phone region: Estonia
More than one mail account (all IMAP, if that is important). 1st mail account has been added, then 2nd and then the 3rd - all three worked fine together. But, then I have turned on the Synchronisation to iCloud and 1st and the 3rd have disappeared. I have further added 1st and saw 2 mail accounts for some time, then 1st disappeared again.
My iCloud account is connected to the 3rd mail account e-mail address, but that disappeared, so it’s not the case.
After the iCloud sync was turned off, it didn’t disappear any more.
The mail accounts kept disappearing over 5 times.
PS: I will test further, if that isn’t the iCould sync, I’ll add more comments here.