Earlier this morning I published a Collector map. In Collector I could see that I had 2 related layers (wCustomer and MasterAssignments):

I then closed Collector on my iPad and reopened it. Then I could only see one set of related records (MasterAssignments):

The webmap that I'm using in Collector still shows that both layers are related:

wCustomer is a related table.
MasterAssignments is a related feature class.
Both are related to the original data (wMeter) using the TapNumber field.
Does anyone know why wCustomer is not showing up in Collector as a related record now?
Many thanks
David