Interesting that since respawning the enderdragon; the new Portal works fine for me (Bedrock Win10) - also, the new portal landed me in a place that I had already explored, and still worked and generated end cities etc. Also (so far) all the portals that send you back to the main island have worked; including one I had used ages ago.
I've been back and forth a few times, no other issues so far. However still a bit strange that a fix hasn't been forthcoming already - it's a pretty major issue effecting a lot of people...
I posted over here https://bugs.mojang.com/browse/MCPE-19699 as my problem wasn't the loading of the game; but now I see they are very much related. 2 worlds have this issue; plus my son's on a different PC! Looking forward to a fix!
To add to the above... The exact same issue now occurs with my other world (both are survival and on Bedrock Edition)!
In my 2nd game; the teleporting / death in the portal happened a bit different - sometimes it would get stuck and I'd sit there in blackness without taking damage; but dying was the only way out 😞
[Luckily, i've died most times and so haven't quite had the game loading crash that others have... and when dying, you re-spawn several blocks above your bed... which I think may be related...maybe some co-ordinate thing is creating issues. ]
Just wanted to comment as I've got exactly this issue. Except I've only got one Gateway (killed ED just once so far).
I was going through my end gateway portal for the first time in a few months... Was using the water method. Got stuck in bedrock as described above. The first time, I was "released" and promptly fell into the void. All other times since, I haven't been able to get out, and die from suffocation in the endless teleporting loop thing. Doesn't seem to make any difference if I use the water or a enderpearl.
Is this an issue that we should expect a fix for, or do I need a workaround... eg kill the EnderDragon again and see if a new portal works?
Can anyone confirm if the new update has resolved this issue? I'm not able to test at this moment.