I have no way to really explain what's going wrong. No errors are thrown my way, but most (if not all?) Timeless Isle rares have stopped tracking since a few updates ago.

As in it doesn't notice when you kill them? Always thinks they're already-killed and so doesn't notify you?

No, it doesn't track them when they appear on the minimap, when their nameplate is in sight or when hovering over them or targetting them. No alert, no click-target appears, etc.

Could you perhaps send me a screenshot of your map and the silver dragon mob-list popup from the icon on it? Like so:

My SavedVariables file in case that is of any use to you: https://files.catbox.moe/dohsr1.lua

I usually have SilverDragon rare icons and the mob-list icon disabled because I prefer to use the map rare icons from another addon, but here's a screencap of it after re-enabling the mob-list icon:

Note that I took the screenshot after having just killed Huolon, Watcher Osu, Champion and Rock Moss.

I also recorded a few videos in case those are of use.
Huolon and Rock Mass shown in this video, targeting, hovering and nameplate not triggering an alert. Show SilverDragon settings as well to verify that I have all the right things enabled (haven't changed any of those settings in many many months anyways). I also open BugSack at 1:45 in the video to show that there's been no errors in the session that could have interfered with the functionality: https://www.youtube.com/watch?v=2eEHpj7z1bo

I test with a rare mob that has a minimap vignette as well just to rule that trigger out as well. I show that the mob is enabled in Mob settings and perform a reload: https://www.youtube.com/watch?v=tm171YOznQo

Note that I have also tested with all other addons disabled, which made no difference.

I'm having the same issue. I've notice that only works with rares marked at silver rares by blizzard. But the normal elite rares are not working. It's works with Zesqua, Rattleskew, etc, but doesn't work wiht Bufo, Jakur of Ordon, etc

I've notice that all those rares not working say they were last since 5 days ago. I didn't change anything since then, but I saw them in Remix, not in retail.

I have a theory that Blizzard changed the way the vignettes work slightly on the timeless isle in preparation for Remix -- making them zoneInfinite (so their data is always available wherever you are in the zone). If they weren't this way before, that'd explain the change.

If I'm right about this being what's causing the issue, the new version I released yesterday with 0d70a1e should fix it. After you've updated, could you let me know if that helped?

Thank, the pictures were taken after I updated the addon yesterday, so sadly that fix doesn't work. I have to check if it works in Remix, I'll let you know if works there.

It's working fine in Remix

Just chiming in to say that it indeed doesn't seem to be working in retail still even after updating the addon.

Sorry about the colours, I play in HDR. However you should be able to see that it says last seen 7 days ago when he's standing right in front of me, even after hovering over him.