1. When the Controller faces issue in communicating with the AP, it will generate a Heartbeat loss event. Below is the link for more information.https://support.ruckuswireless.com/articles/000003945https://support.ruckuswireless.com/articles/000001658
2. How are you identifying that the SSID is missing from the AP?
From the Controller, click on the AP, scroll down and see the list of SSID it is broadcasting.
Alternatively, you can also login to the AP CLI and check the list of SSID it is broadcasting using the command "get wlanlist".
3. Currently 128 is the limit on the controller. If you want more for the same SSID, then you might have to go with the "Radius" based authentication which will have MAC based authentication.