Dear K. Nisa,
I have this problem, Can you give to check this Email user: linh.ptt@redbullvietnam.com ?
When having new email in inbox, it appears in some seconds and automatically deletes from inbox. Because she uses outlook so she did not know, but now she wants to use with mobile and this problem appear. Since 1 – Aug – 2016, the inbox does not show new email.
You can see as below (note at the red box):