I've had different phones and it's never the same... On Apple I think I had to use either a comma or a semicolon and a space after that and it automatically changed it. On one phone I could do it by clicking on Update (really annoying when you want to add multiple new tags). On one phone I couldn't do it at all. And on this phone (Android) it works with enter. Who knows why it can't just be the same for everyone...