Android: The multiplayer gameplay continually switches off.

^{Update by [Mojang] Mega_Spud (Jay Wells):}
Verification builds:
1.12.0.3 beta | Android: Yes
1.11.1 | Android: Yes
1.10.0 | Android: Yes
1.9.0 | Android: Yes
1.8.0 | Android: No (Untested - community reported)

Summary:
Players on Android used to be able to create and host a world using a WiFi hotspot, that nearby players could then join.

(Apparently this was working in versions 1.0 - 1.8, but stopped working again in 1.9 - 1.12)

This is no longer working, as the multiplayer option gets disabled when joining a world

Repro Steps:

1. Turn on Mobile Hotspot on an Android device
2. Have a nearby player connect to the hotspot
3. Launch Minecraft on Android
4. Create or open a world (check that Multiplayer is enabled in the world edit menu first)
5. After the world has loaded, check the multiplayer option via the in-game settings
6. Have the nearby player try and locate the game in the friends tab
7. Try and invite the nearby player to the game

Observed Results:
At step 5, the multiplayer option is greyed out and turned off.
At Step 6, the nearby player does not see the world available to join.
At Step 7, inviting the nearby player appears to work, but does not succeed (no invite is sent or received)

Expected Results:
Players should be able to successfully set up and host a local world using a hotspot.

Screenshots/Videos attached: Yes

Notes:

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Original Description:
There is a bug in Minecraft Bedrock where LAN Multiplayer is not working. When creating a new world, the multiplayer gameplay is switched on but, if the world is played, I (the host) can't invite my friends to play via mobile hotspot or LAN because it switches off automatically.