Having the same issue on Windows 7 - Browser app in Chrome.
Using r212.2 64-bit
Using built-in Google Play object as well. I can log in, all achievement functions work.
Can submit new scores and retrieve my own scores correctly, but retrieving list of other players' scores fails.
GooglePlay.HiScoreMyFormattedBest shows correct updated value.
GooglePlay.HiScoreCount is always zero.
GooglePlay.HiScoreNameAt(0) is always empty string.
GooglePlay.HiScoreFormattedAt(0) is always empty string.
What's weird is that fetching social leaderboards will report only my own score in the list, whereas public leaderboard is always empty. I added multiple accounts to the G+ each with their own scores, so the social list should have those other scores in there, but only my own score shows up.