@Roel van Zwieten can you try setting the synch rule Batch Sync to “On Changes”?
 

Hi,

If you can modify the app:

One of the way is to set the Customer  Entity as push enabled entity. So when ever a customer get created in the back end will push that to the device. Other option is to use ‘On Demand Sync’ capability on the Batch entity where you user can download additional data on demand. So you can download newly created Customers from the back office which are not yet sync to the device. So still you can keep ‘Customer’ as a batch entity + adding  support on ‘on demand download’. But all above need a modification to the app.

Via configuration

If you need to achieve this just from configuration, then keep batch data frequency is to 15 (Which is the lowest) is the safe option.  ‘On Change’ is not suitable for fast moving data like customer. It’s is more suitable for entities like ‘Country Code’  which has very low change frequency. Putting On Change to a fast moving entity can cause performance issues. 

Hope this helps!

Thanks both, putting it as ‘On Change’ or every 15 minutes should both be fine in this case.

Looking at this further it seems like customers are only shown if they either have existing tasks against them, or are defined as the customer on an object, correct? So if I would want to show a newly registered customer, I would also need to set up an object for this customer in order to create work against it? And am I then correct that this condition can't be changed (without a modification)?

15 min Batch shedule recommended as the entity can have high data change frequency.  

Yes you cannot change the default filter without a modification.