I have the same situation as several other posters with an ADP2108-3.0 whose output sits at about 1V. With the output at 1V, my circuit is drawing about 45 mA.
I have added a 4.7 uF X5R 0603 input capacitor across Vin and ground, still doesn't work. If I disconnect the output load (I have a series current sampling resistor), the output sits at 3.0V like it should. The circuit is on a 6-layer PCB,
There is a dedicated ground layer. I've used one of the recommended inductors, and 10 uF tantalum input and output capacitors (before adding the 4.7 uF ceramic input cap).