Source: Curse

One other bug I've noticed is occasionally when logging in, I'll get an achievement toast about finding a Skyshard. It may be because I have two Skyshards sitting in my bags, but obviously it still shouldn't be triggering the "found" notice. And it happens so randomly that I can't figure out the cause. I'll go weeks without it happening, and then all of a sudden it will happen again.

The detection is likely very sketchy as it tries to find items that it previously missed, by scanning the inventory directly. It might be difficult to reproduce it, but perhaps the conditions could be isolated and a /reloadui would suffice?