On domain separated instances you will have to take into account the domain of the Dynamic Share's Business Rule. Each Dynamic Share will have a corresponding Business Rule to process the insert/update/delete of a record. This Business Rule will be created in the domain of the current user. That Dynamic Share will then only apply to that domain of records.
For example, if the user creates a new incident record in the Top/Alpha domain, the record's domain will be saved as Top/Alpha. If the Dynamic Share was created by a user in the Top/Beta domain the Business Rule will be created in the Top/Beta domain. This will then mean that this Business Rule, and therefore this Dynamic Share, won't replicate the incident we just created in the Top/Alpha domain.
We recommend that you change your domain to “Global” prior to creating your Dynamic Shares. If the Dynamic Share was created under the Global domain than there is no issue as it will then apply to all domains. It is possible to set the domain of this to Top which in our example above would apply for both Top/Alpha and Top/Beta.
You can see all your Dynamic Share's Business Rules, and their domain, by going to the Business Rules module under Replicator.
The Business Rule's domain will be set to the user's domain upon creation. This is handled internally by ServiceNow's scripts. So we cannot enforce / override this by setting the domain to global automatically. This issue currently being reviewed and may change at a future date.