Hi!
Yes, very likely. It takes some time for Threema to “notice” which device is used; and I noticed that was not consistent the first few days: some messages were send to the “old” installations, some to the “new” one…
Good luck! Just a tip: the easiest way to install apks in Anbox ist sending them via Threema; you can install them directly by tapping the incoming message with the apk. No hassle with adb or ssh and with hidden paths etc…