Before I explain, I tested this a few different times and I got the same result.
If starting with no streak (0 days) and I complete my XP goal for the day of lets say 20xp on the computer, it will not sync to the app properly. I personally use chrome (tested on both Ubuntu 14 and Windows 8.1) and using the IOS app.
But, the app does actually register that I've earned the XP as shown from the weekly leader board and the graph in the app which visually displays that I surpassed my goal for the day. I've tried closing and restarting the app in addition to uninstalling and re-installing the app to check if it would then sync, but it doesn't. When I re-open the app, coach will say I still need to earn 20xp (or whatever my current goal is set to).
If I then proceed to complete the 20xp on the app, and check the computer, it automatically syncs and shows i completed 40xp (both on the computer and the app). After completing the goal on the app once, the next day coach will properly sync with the computer if i complete my goal there.
This seems to be just a small bug, but it seems that after completing a daily XP goal on the app once, the app syncs properly.
I wonder if it is related the different streak systems between the computer and the apps? The website uses a global streak. Any combination of courses can be used to generate XP towards your streak. The Apps use language specific streaks. So, you would need to reach your goal in each language to maintain a streak in each language on the app. This would make it so that your app points counted on the computer, but not necessarily the other way around. Think that might be it?