wl photo gallery will not sync with google drive,
Google drive more likely will sync with your original folder/ folders in your My pictures library or what or where the folders are located on your computer that you uploaded to google drive.
wlpg reads these same locations on your computer so it, (wlpg) will possibly pickup on the changes if any are made,
So all you can do is check the location of the folders you uploaded to g-drive and see if the folders are updating/ sync with g-drive.
Then go to wlpg and use F5 and possibly wlpg will refresh the page and reflect the changes/ additional files.