Honestly, we have no solution yet for this limitation.
Google often has changed API(also policy) for Photos.
It is assumed that Google would like users to use photos in the manner (or app) they provide rather than in a third party. We will continue to research to find the best way while respecting Google’s direction.
Have the same problem too… I had a webchat with Google Support when I found out I could no longer sync my photos and they said it separated from gdrive due to it being confusing!
Now, I cant even backup my own personal photos and they suggested I make a feature request!.. They are my photos… how dare they prevent me from backing them up!
I thought there was hope when I saw this app, but then had the same 0kb issue, so hope the devs can find a why to resolve it.