Related Tables Work Great in AGOL/CollectorClassic, but not in Collector/FieldMaps?

[Anonymous User]

I have a feature class with two tables related to it.  Published the feature and tables to a hosted service.

In AGOL, I can see related features from both tables as well as edit and add records to both.

If I put that service into a webmap and open it with Collector, I suddenly can only can see features from one table. The second table looks blank and does not allow me to add records ("Unable to create feature"). I get this same result if I open it in Field Maps.

However if I open the same webmap in Collector Classic it works perfectly. Both tables show all related records. Both tables allow me to edit.

.....why?

More importantly - how do I get this to work in Collector/Field Maps?

[DougMorgenthaler]

@Anonymous User can you clarify what platform/OS are you using?  You mention not being able to "see" the features - are they not displayed through the popup, or on the map?

[Anonymous User]

To look at Collector and Field Maps, we are using iOS.  Using the same to view Collector Classic (where everything works).  Viewing AGOL via my desktop using Windows 10.  

In Collector/Field Maps I can select the "second" related table, but it does not show any related records or allow us to add new records (see the first two images attached).   Whereas in Collector Classic, I can go to the exact same webmap, and feature within the webmap, and see all related records and make new records as well (latter three images attached).  

Same webmap, same feature service, same OS - just different apps.  (And of course, we really need it to work in the newer ones rather than the older.)