I recently got a new phone (Samsung Galaxy S8) and i noticed that this "ꜜ" symbol renders as a box in the Chrome app.
My old phone, a Huawei Honor 8, did not have any problems with this symbol and it does render correctly in all other apps on my S8.
I'm not sure if the Android version has anything to do with it but my new phone is running Android 8.0 while my old phone is still running on Android 7.0.
I found this question: https://superuser.com/q/886193/707282
It's about Chrome on PC but the problem seems to be the same; I have the font installed on my system but Chrome doesn't use it to render the character.