When adding Web Map Tile Service (WMTS) or Web Feature Service (WFS) layers with sublayers to a web map in ArcGIS Online, the layers do not get added.

Workaround

1. Add the layers to ArcGIS Online's Map Viewer Classic. This stores layer identifier information properly.
2. Save the web map, and open it using the newer version of Map Viewer.
3. Copy the JSON details associated with the operational layers from the classically produced map to the new map.

The layers function as expected.

Schritte zur Reproduzierung