One of the recent supportability wins was an increase in the maximum number of objects allowed in an Office 365 tenant. Prior to the increase, the default limit was 50K objects for all customers. Unfortunately, that meant that many of our largest customers would hit that limit and be unable to synchronize any additional objects until they contact Support and requested an increase.
Through a partnership between the various Office 365 PGs, PQO, and GBS, we instituted a change where anybody who verified a custom domain would automatically have their object limit increased to 300K objects. We are also in the process of backporting that change so that all existing customers with a verified domain will have their object limit increased to 300K. The combination of these two changes should drastically decrease the number of times customers have to contact support to be able to complete their synchronizations.