From what I can gather by reading other people's posts is that gametime tracking SHOULD be working. I've been using 2.0 for about a month and a half now, and at no point has Galaxy 2.0 ever tracked any of my Xbox game times. This has continued to irk me but I figured maybe game time wasn't a support featue for Xbox integration. But I decided to disconnect the integration and add it back and noticed that game time IS suppose to be supported.

tl;dr - Is there any reason/fix for why my Xbox gametime isn't being tracked on ANY Xbox game?

Same here, been using for a while and also tried disconnecting and connecting the Xbox integration, for me it shows most of my games but doesn't show the game time and the achievements. Have you found a way to fix it by any chance?