Magsafe power adapter not detected

16" Macbook Pro - I have a strange issue when swapping between charging in a USB-C port and then using the Magsafe port.

I work all day with an external display (own power source) plugged into thunderbolt/usb-c port on macbook. This is also charging macbook.

At the end of the day I close the lid of the macbook, unplug thunderbolt external monitor and a few minutes later in another room I plug in the magsafe charger. The charging light on the plug can be green or orange. No sound is made when I plug it in.

When I open the lid, the battery icon does NOT register the power adapter.

I need to restart for it to register the magsafe power adapter.

Any ideas?