I found lots of questions regarding this - and I am almost ashamed to ask it myself.
But no matter how hard I try, I simple do not get the Maps API running
I am also having the same issue and know I kinda know what causes the problem ( not the solution to it though -yet- )
Try to run your app of other phone than your HTC One. Because I have the issue with my HTC One but when I run it on my S3, it runs perfectly.
Try and let me know please
EDIT
I solved it. But not sure what was the exact solution but here what I did as steps: 1- I displayed the developers options in the phone settings use the 7 times clicks in 4.2 OS 2- Allowed Mock Location 3- Selected my app in the "select debug app" 4- uninstalled my app 5- re-installed it 6- run it and waited for 30 seconds then the maps showed
Hope this helps