I'm having the same problem here. The difference is that it doesn't help to restart ionic serve.
I write my code, and my console window says that my ts files are changed. My app reloads in my browser, and things seem fine.
Then i notice that things haven't really changed. The new code doesn't seem to be added to the app.bundle.js file. I did some change today, and checked the file in finder on my mac, and it says that the file haven't been updated since November 13th.
I am new to this, and really have no idea where to look, to find the reason why the new code i write in my ts-files never actually makes it to my browser. Does anyone have any idea where i can start looking?