Pydeck: Terrain model, how to avoid reloading when moving the camera

When displaying an elevation modele, the terrain disappear each time the camera moves.
On the online example here :TerrainLayer — pydeck 0.7.1 documentation, it works as expected, but when moved to streamlit, I get a non expected behaviour.

I am missing something ? is there a workaround ?

TERRAIN_IMAGE = "{z}/{x}/{y}.png"
 ELEVATION_DECODER = {"rScaler": 256, "gScaler": 1, "bScaler": 1 / 256, "offset": -32768}
            SURFACE_IMAGE = f"{{z}}/{{x}}/{{y}}@2x.png?access_token={MAPBOX_API_KEY}"
terrain_layer = pdk.Layer(
                "TerrainLayer", elevation_decoder=ELEVATION_DECODER, texture=SURFACE_IMAGE, elevation_data=TERRAIN_IMAGE

            view_state = pdk.ViewState(latitude=46.24, longitude=-122.18, zoom=11.5, bearing=140, pitch=60)

            st.pydeck_chart(pdk.Deck(terrain_layer, initial_view_state=view_state))