This bug was discovered with the current code base in LabVIEW 2025Q3, but reproduced in LabVIEW 2020 with the built-in Icon Editor

Summary

Using the Delete key to remove a layer behaves differently than when using the Delete Layer button. It will delete the layer data and remove it from the layer list, but it still behaves like there is an empty layer selected.

Deleting the layer with the Delete key and then filling the header:

Deleting the layer with the Delete Layer button and then filling the header: