I can't join this 1 world anymore.

Observed Results:
This is similar to MCPE-36190 but there is a slight difference that might indicate the error. 30 seconds into the video, my character joins the world but on my side of the story, I am still trying to locate the server. My armor is on, my location is fixed and my current skin is applied but I can't take damage. My computer is Windows 10 joining my gf's world who's playing on iOS. We have been playing a lot in the world and defeated the Ender dragon. Soon after we defeated the Wither and that's the last thing to happen. We tried copying the world and trying again but I think the world file is corrupted. We are both on the latest verison but the screen is stuck on Locating the server. In the video I try to click cancel but that doesn't work either, it doesn't let me abort. She leaves the host world, which should automatically kick me out, it still keeps loading. I have tried waiting about 3-5 minutes. I don't think I need to wait any longer.
Steps to Reproduce:
1. we played a lot
2. The Wither was defeated(probably the cause - not sure because it was random)
3. I can't connect to her world anymore.
Expected results:
Just as any world joining process, which works on other worlds except this one in particular, it goes very fast and successfully. If there's a way to diagnose or verify the files or somehow fix the problem that would be helpful. Thanks.