Device assigned to an area doesn't show in that area

Hi, I’m brand new to automation.
Have a SLZB-MR2U, one side configured as Matter/Thread, the other as a Zigbee co-ordinator.
HA running on RPi.
Trying get my 1st Zigbee device working (an AVATTO ZDMS16 dimmer).
It shows in Integrations/Zigbee Home Automation/Devices.
When I click on it it tells me it’s in “Snug”.
But, when I look in that area - it isn’t there.
If I go into Snug and try to “add an existing device” it takes me to a Devices page that doesn’t show my dimmer.
Where am I going wrong?