Hi Josh. I'm having the same issue. I'm using the python client library, v201603 for your reference. I'm using the same top-level MCC for both AccountLabelService (which works) and ManagedCustomerService, which doesn't. If I use the the "AccountLabels" in the predicate of the selector, it fails with the following:
WebFault: Server raised fault: '[InternalApiError.UNEXPECTED_INTERNAL_API_ERROR @ com.google.ads.api.services.common.error.InternalApiError.<init>(InternalApiErro]'
However, if I just include "AccountLabels" as a column but not in the predicate, the query works but the results do not contain any "accountLabel" field. Below is my selector passed into ManagedCustomerService.
{'predicates': [{'operator': 'IN', 'field': 'AccountLabels', 'values': [4038216, 4038261]}], 'fields': ['AccountLabels', 'CanManageClients', 'CompanyName', 'CurrencyCode', 'CustomerId', 'DateTimeZone', 'Name', 'TestAccount'], 'paging': {'startIndex': '0', 'numberResults': '500'}}
Pls help, thanks!
Yang