On android you have to download the music off the marketplace for free so check you have done that. For the zombie Pigmen check you have no texture packs enabled.
I can confirm that this effects 1.16.0
Sorry I managed to find the resolution to my problem with my account. It doesn't need deleting anymore.
My sister has been having the same issue on her Kindle Fire 7 tablet as when we try and play multiplayer together (me on my Nintendo Switch), I cannot join her worlds but she can join my worlds and she can join servers such as the Hive.
I think the error may be caused by the host of the world's internet having dropped in the middle of a time when they are hosting their world, however, I can't confirm this. I feel this is a really important issue to get fixed for the upcoming 1.16 update as currently me and my sister can no longer play our survival world together.
By the way, I thought it was important to say this, but even when this message comes up my sisters Microsoft account is still connected. We have tried signing her in and out but it has done nothing.
I believe that this is caused since on a kids kindle fire tablet, the web browser is disabled with no way to enable it and to log into a microsoft account it requires use of the web browser and therefore rejects it. Something was presumably changed in the latest update to effect this.