What do you mean by platform tracker - are you wanting to know which Xbox 360 games track playtime?
I've noticed that many of the 360 games do track playtime, but they need to be played on Xbox One. If played on a 360, I don't think any of them track playtime, so that's why a lot of previously played games won't have playtimes shown.
the 360 did not track time played. There used to be a site that would scan your profile every 5 min to get your current game and then would keep track of how long you played games but it was not an official source.
A few years ago I noticed a 360 game clocking time played on the X1 dash. I reached out to a person on Twitter I know is part of the group that runs achievements and stats and he confirmed it was a mistake and that 360 games should not track time played. If they do its just overlooked by the team.
No idea why every game 360 or otherwise doesnt track time played.. its silly.
I noticed this too, it looks that some 360 backwards games but not all (for example halo 3)
Maybe microsoft will put an option to check the playtime from backwards compatible games or something
A list of some games that I notice have playtime (not in any specific order)
GTA san andreas
MGS: Peace Walker
Persona 4 Arena
The Orange Box
Perfect Dark Zero
Nights into dreams
Silent Hill HD Collection