I play Minecraft windows 10 beta and just recently downloaded the 05/07/2020 update. Before the update, I had a prebuilt nether portal from the same world of a previous version and after the update the animation would function properly with the whole wiggly screen and music getting louder but when I was supposed to spawn in the nether the whole app crashed. It happened two or three times then resolved itself then functioned properly for about an hour and a half then started crashing again when I would try and use the nether portal going both ways.
Thank you for your report!
We're actually already tracking this issue at MCPE-66678, so I will resolve and link this ticket as a duplicate.
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