Also having same issue on Windows 10. Everytime I start up the game I get the Welcome To Beta 1.16.210.55 screen with the UNLOCK button, but each time I press the UNLOCK button I get the Unable To Connect To Marketplace message. I have also uninstalled and reinstalled Minecraft and still get the same error.
I am having the same issue with my Xbox 360 controller. I am using an Ostent wireless receiver and it was disabled by Windows 10 2004 update. I was able to get the receiver recognized by Windows 10 by changing the hardware ID in the driver to 0291. Windows now recognizes the receiver and the Xbox 360 controller shows up in Control Panel. I am running MC Bedrock ver 1.16.4 and it is not recognizing the wireless controller. I am able to use it on Minecraft Java Edition via Steam. Hope this extra info helps in recreating the issue.
This is happening while using both my Microsoft Xbox/PCE bluetooth controller and having a wireless mouse.
Create a new world.
Play the game for a few minutes and you get a message on the screen saying controller has been disconnected even though the home button on the controller stays lit solid.
Wiggle mouse slightly and controller is reconnected to the game.
Observed Results
I have discovered that this is being caused when the mouse goes into power save mode. My wireless mouse is rechargeable so when I connect the USB charging cable to the mouse enabling the mouse to stay awake at all times the controller stays connected.
I have also gone into Windows settings and disabled power management for the bluetooth devices, but I still have the controller disconnect if I dont keep the wireless mouse plugged into the PC.
Having the controller plugged into the PC does not fix the issue, the controller still disconnects if the wireless mouse is not connect to the PC via usb cable.
This issue has been happening since the GDK update.
Expected Results
The controller should stay connect to the game without having to have the wireless mouse connected to the PC via USB cable.