Thanks for reaching out. Have you checked other devices to see if it's happening there too? Also, our Help Center article provides more info on how to troubleshoot live streaming issues: https://goo.gl/C9E7Qo . Let us know how it goes.
Sorry for the delay. To upload videos longer than 15 mins, make sure your channel is verified with your mobile number. Also, take a look at these tips for videos stuck during upload: https://goo.gl/1jwAc1 . Hope this helps.