I think I've found a few references about the Win 8.1 WMC channel update issue on the DVBLogic forum:
1. This thread
mentions channel update problems after W8.1 update, plus several mentions of the *.channel_data file being left behind.
2. This thread
has mention of a similar issue with channel update not working with IPTV.
3. In this thread
, the 4th post (by Oberon) mentions that even Microsoft's own samples don't work after 8.1!
From what I can see, version 4.6.0 seemed to be out when W8.1 came along (RTM Aug 23, 2014) although the people having the problem in the threads seemed to be using version 4.5.0. Either way, I'm hoping that one of the subsequent DVBLink server releases fixed the issue, based on the assumption that there would be many more people (or more recent posts) complaining if it wasn't. But the trick will be to find a release that still supports the 1Geek tool. These seem to be the release dates of later versions:
DVBLink 4.6.0 release: circa Jul 03, 2013
DVBLink 5.0.0 release: circa May 29, 2014
DVBLink 5.1.0 release: circa Dec 08, 2014
DVBLink 5.5.0 release: circa Jul 21, 2015
I've found version 4.6.0 so I might try that to see if it fixes the issue without breaking 1Geek. That said, I think version 5.0.0 is more likely to have the fix, but I can't find that version and I think it's less likely that 1Geek will work.