I have an strange issue with lost accounts when I activate 'Global Administrator'.

Following happens:
I have an existing account that appears under 'Accounts'.
When I activate 'Global Administrator' the account disappears from this view.
The account is only visible via the search for Admin-Accounts.
When I deselect 'Global Admin' for this account, the account is also lost from this view. It is only detectable when I use a customized seach formula
(|(zimbraIsAdminAccount=FALSE)(zimbraIsDelegatedAd minAccount=TRUE))

After that I deleted and recreated this account.
Same problem. User ist not listed unter 'Accounts'.
I checked the account with
zmprov -l ga user@domain.com
but could not find any noticeable problems.

Any hints to solve this problem would be great.

Kind regards