This is happening in Realms. I currently pay for and manage a Realm that myself and a few of my friends play on Survival. 

MCPE-146959 is marked as resolved, but this problem is still occurring so I am creating a new issue.

The issue seems to be that when using a Nether Portal, occasionally you may warp in underneath or adjacent to the destination portal.

I experienced this issue twice today in my Realm. Once when portaling from overworld into the nether, resulting in me falling into lava (lived due to totem of undying), and once portaling into the overworld from the nether, resulting in near suffocation (was able to dig out). Extraordinarily inconvenient bug, definitely NOT resolved.