Why does the multiplayer button in Minecraft PE change from on to off?

I just downloaded Minecraft about two weeks ago and I am trying to invite my friends to come to my world.
When I go to the menu, I click on invite to game and chose my friends from the online list. When I click invite they don’t get the invite.

My friends were able to invite me and it showed up and I was able to go into their worlds, but they never get my invitation.

I have tried with multiple friends, I have tried to connect to the same Wifi as them, I have tried swiping up on Minecraft PE, and I have tried re-downloading Minecraft.
It is also updated to the latest update as for all of my friends.

Also, sometimes when they are in Minecraft and I go to invite them, it shows all of my friends as being offline even though some are online.

What could cause these behaviour and how could I fix it ?

UPDATE: I figured out that when I go into the world settings and click on Multiplayer, it shows the multiplayer button on and it is on Friends of friends and the Open to LAN Players is also on. When I open my world and go into the settings, it shows the multiplayer button being off and it’s grayed out so I can’t turn it on or off (which I know it’s supposed to be grayed out in the setting while your in the world) and I’m not sure if that’s why my invites don’t send. I have also made sure that my game settings are on Wifi and Cellular and it is set to use Cellular. Please help me! 🙁