Steps to reproduce

1. Define a detail subapp that shows Magnolia metadata fields like "mgnl:createdBy"
2. Create a new node using such Detail subapp

Find a LM attached with the required Detail subapp, which defines a testApp for it.

Expected results

Field is filled with the correct information, in this case, the creator username.

Actual results

The field is left empty. However, if the field is removed from the detail subapp and a new node is created, the field will be filled without issues.