On the Meraki portal it should state the last known IP of the access point. Can you please confirm and see if it shows one, if it does please try and see if you can ping the IP address of that device. What kind of layer2 infastructure are you using? Do you utilize VLANs ?
Do you have a combined network? Do you have more than just Meraki APs (Meraki Firewall or Switches)
If so you will need to make sure that when you go under event logs you are selecting event logs for access points at the to left of the screen.
Cloud Network Engineer | cloudIT
Certified Meraki Networking Associate
Kudo this if it helped! 🙂