You seem to be doing it correctly.

I added a random image into WD.
I then Previewed it, right-clicked on it and select Save picture as... to discover its filename.
Without a Name, is manifests as nnn.jpg.

I then Named it filename="photo1" and did the above and got photo1.jpg.

Can you try this?

I tried on two Variants and reduced the image size on the mobile one.
Both showed as photo1.jpg. The mobile variant one has an extra class of xr_rn_ .

Acorn