Another strange error ISPConfig3 in the last version. Add your site as admin, i assume client later. When assign an account that previous page is part of a new client. All the customer sees the good site of the panel, but can not change anything in it. Does it have to be so?
This is the intended behaviour. Users shall of course not be able to assign a larger webspace for themself or add other options to a website then the administrator has assigned to them.