In order to obtain a better view over your issues I will ask you to share your project name with us if created in our in-browser or Windows client in a private ticket
. If you use VS extension for development consider attaching your app to the thread.
It would be helpful if you guide us where we should look in the app's code.
In the meantime, I recommend using our debug on device
feature and investigate the cause on your own.
I look forward to your reply.