We'd like to help. What device are you using? Does this happen across devices/browsers? Also, have you taken a look at our Help Center resource on common uploading errors and how to fix them: https://goo.gl/r2zzEa ? Let us know.
Please take a look at the Help Center as it covers many troubleshooting steps that you can try to resolve this issue. Also try uninstalling and reinstalling the app which may be of help. Keep us posted.