I do not want to be suspicious or something just thinking that actually Leona never spoke about Glassheart as a single she would like to release,in all the interviews she always mentions other singles as her favorite like fireflies, unlove me, i to you..and she said that trouble was her main favorite (maybe this could be just marketing campaign, promote the single you release)...plus in an interview the interviewer asked her if she would like to release an uptempo..and she mentioned shake you up..
In addition, ok that the label wanted to stay true to what Leona is, but when a song is good , it's just good! ..you can definetely say GH is an instant hit(like Burn) and back in the days it was much powerful than collide.......and to me I find hard that the label did not see the potential of GH as lead single, that preferred release collide trouble and lovebird before GH. It's not like oh well I do not if releasing happy or broken, or BL vs better in time that are both really good single choices.
So now that the problem seems choosing the single, isn't way better if more people (i don't mean everybody) can hear the 6 potential singles,and not just the label members,to see what's the best reaction.. This is just me thinking in a rational way, the comment do not want to attack anybody