Null trap-id in WFS feeds

In the WFS feed for my-projects-trap-records the trap-id field is NULL. Similarly the trap-id field in my-projects-traps is NULL.

It would be helpful to be able to relate the records with the traps by a reliable key. I note that the CSV file exports the trap-id.

I thought these fields used to be populated. Is this an oversight?
The same would apply to bait stations and monitoring stations.