Multiplayer disabled on Minecraft world in local console split screen suddenly, why?

So my teen and I (dad) played Minecraft Bedrock 2 days ago. The world was created by my teen.

Then today, we can't open the world. It says "Multiplayer disabled", check parental controls. So I went and removed restrictions on everything I could find in my teen's account and mine. I've set her restriction to age 19+ (unrestricted), rebooted many times, but still didn't work!

We don't want to abandon or delete the world since we've been building it for more than a year already, so much progress!

So last resort was to delete her profile's local storage, then rebooted, then accessed the world again, it still has the world name, and "unknown"

sub-title, then it synced with the cloud, took a while, then we were able to play it again back to where we last stopped.

We tested it, played for 2 minutes, Save and Quit. and voila! The multiplayer disabled flag is back on that world.

I did the deletion steps and syncing once more, it worked, BUT WE CANNOT go like this wasting an hour everytime just to delete and sync.

Can anyone tell me how to contact xbox support by phone from Australia? It seems they don't allow phone calls, the chat asks doesn't work as BOT verification on bikes, buses and all sorts of images doesn't work too.

I'm at my wits end, can anyone help me please.

Edit:

I've created a new test world using my teen's account, then I joined using my parent profile/account, save and quit using her account, and the world does not have "Disabled" flag. I was able to play the world with both accounts. So what's going on with that other world? Why is it having Multiplayer disabled" message when my teen can make world and I can join without any issues?

If I click "Learn More" button in that pop-up window with the "...parental control" message, it takes me to the options to buy Game Pass (ultimate, standard, core). We didn't need to buy anything while playing that world, we played with split screen only.

:)