I had the same problem and I think it might due to the Bordless option, if u manage to open the game again change it to Fullscreen and it will be back to you as a normal (and not background) app.
This worked for me after seeing this coment in another forum:
Napsterbater:
If this is Windows 10, you will need to edit your Config file and disable Borderless Window Mode.
See this thread as this problem was found in the Preview (beta) build for Windows But has not been fixed yet.
https://forums.battlefield.com/en-us/discussion/comment/27622#Comment_27622
The link to the forum is this
