So for me Rukhmar Boss Notification stopped showing up, timer works still but no popup. Tried fresh addon install - didn't fix it.

Can you clarify what the "popup" is? And does it work on other bosses?

The only alerts that should play are:

• Sound alert before spawn (10 sec default)
• Sound alert + game icon flashing (if you're tabbed out), on boss combat detected

There used to be a /say message, but was removed a long time ago (in 8.2.5 due to Blizzard API restrictions).