Does the number of games already on hand on my end affect how long the manual scan takes? Like for a new game with achievements that is just downloaded, even after manual scans, it will take maybe 40 mins to 1 hour for it to acknowledge that the new game is already downloaded and reflected in Exophase with the corresponding achievements tracker and completion status or missing in the profile where it should be the latest in "last played". Previously, it takes at most a few minutes (the number of games on hand didn't change by much). Yea, probably like you suggested, to bypass the requirement of checking all the achievements. Also, achievements & games installed have synced to GP servers because I usually check the Play Games app and it is already displayed on the profile but that app is so buggy to use with its frequent lags/freezes (that I always have to restart it) that I am not sure if it's part of the problem.
Edit:
The Fixies: Adventure game and
4x4 Dirt Offroad Parking doesn't seem to be tracking as game owned on Exophase despite being on my Play Games profile ages ago (correct version of games as number of achievements is the same) and I did frequent manual scans but nothing changed.
Quick Crosswords got tracked (completion % and achieved numbers recorded which is zero for both) despite being downloaded the last while the other 2 was downloaded before it. Is there a way to force scan these games to make it able to be tracked?