I've noticed it so far on Hopecrusher, Famu and Nerissa. If I've killed it on my main, on alts it will change raid marker but give no audible alert or popup. Changing Profiles doesn't help.

It does work normally on the mechagon spider rare i farm though

Update: It seems to work normally at around 1-2 hours after my main has killed the rare. I have the re-alert set to 2 minutes though