If we modify /www/admin/banner-edit.php by commenting out the last line, it works fine.
OA_Permission::enforceAccount(OA_ACCOUNT_MANAGER, OA_ACCOUNT_ADVERTISER);
OA_Permission::enforceAccessToObject('clients', $clientid);
OA_Permission::enforceAccessToObject('campaigns', $campaignid);
if (OA_Permission::isAccount(OA_ACCOUNT_ADVERTISER)) {
OA_Permission::enforceAllowed(OA_PERM_BANNER_EDIT);
OA_Permission::enforceAccessToObject('banners', $bannerid);
} else {
// OA_Permission::enforceAccessToObject('banners', $bannerid, true);
}