There is another game where this has happened in called XP level booster and XP level booster 1. Where I got 19 out of the 20 achievements in both games but for some reason the level XP booster 1 game did not sync the achievements to my profile even though I did see them unlock in the game and it shows on the hub that I have them...but the do not appear on my google play profile or exophaseI think it's an issue on Google Play's side as when I view your profile through the app it isn't showing these achievements either. The most recent are in Mobile Legends: Bang Bang and overall it shows 538 total (same as us).
I'd guess they haven't been synced yet server side so the unlocks are showing up local only for now.