Similar problem here:
Had a huge world created in solo play. Doing the Free 30 day trial for Realms so I imported my world.
40-50 hours in and not a single thunderstorm on the Realm copy - weather worked fine in solo. Will likely just cancel the Realm subscription until it works properly.
(xbox one)
This still happens to me - I have 15-20 portals, and randomly will take damage going though any one of them in either direction. Its not everytime but most of the time.
Whatever current bedrock edition is on XBOX one as of this post.
They are all standard minimum sized portals,
some have one end auto-generated, some I built both ends to exact coordinate locations
I have tried clearing more terrain around the portals - including having some free-floating one block off the ground
It is SIGNIFICANTLY worse since I moved my world from a solo world to a Realm.
damage can vary from 1/2 a heart to almost dead from full health - hasn't killed me yet but probably will one of these days.
Always take the damage while it is in the transition screen (building terrain or whatever) where I can't do anything. The majority of the time its just 1/2 to a full heart of damage. But occasionally if the loading screen stays up longer, it is significantly more.
I've tried entering the portals from various angles, directions, side, middle, but no rhyme or reason as to why sometimes I have no issue, and other times I do.
no noticable difference based on number of people playing in the realm - from just me to 4 people. I'm not the only one that takes damage - everyone does.
The damage I BELIEVE is suffocation - and I get the constant tick-tick-tick of taking damage while the destination terrain is being built - so the longer that takes, the more damage I take (WHEN i take damage - which is not everytime but probably 50% of the time)