With the new UI, only one LAN game is visible at a time. If multiple LAN games are available, one of them will be displayed randomly. The other worlds are not visible, and you cannot connect to them.
I have multiple worlds on my LAN, but I am always only shown one randomly at the top of the worlds list. With the old UI, I could always see all the worlds, even if other players had opened a local world on their end. Now I have to quit and restart the game multiple times until the desired world is randomly displayed to me.
Steps to reproduce:
Create multiple worlds on your LAN, and then try to connect to both worlds one after the other specifically using a third device.
The three worlds in the screenshots are permanently online on my LAN, but only one is displayed to me at a time.
This issue is being tracked at MCPE-190764.