Using this thread and some info I found elsewhere on here, I was able to get it parsing the data.

It requires both the flag setting Frank posted above and adding this in the HTTP Reader header setup:

Integer iDontKnow

Get AddHeader   of oHttpReader "Accept-Encoding" "gzip, deflate" to iDontKnow
        Integer iEnable        Boolean bOk
        Handle  hInternet

        Move 1 to iEnable // Or 0 if you wanna disable it
        Get RootHandle to hInternet
        Move (WinAPI_InternetSetOption(hInternet, INTERNET_OPTION_HTTP_DECODING, AddressOf(iEnable), SizeOfType(Integer))) to bOk
I've added it to our base classes, but I wouldn't be surprised if I'm more likely to find it the next time I'm looking for it quicker on here than in the project code...