Well, Blizzard is busy hiring analysts to find where they can cut off another 50% of the staff. That way they can have insane quarterly results. They are likely to monitor our behavior and see we still take it in the *** with these bugs and pay as the loyal customers we are.
Most likely they changed the code so that buff applications (or buff expiry, can't really tell which one it is) fire an event, without realizing that there's a listener on that event that removes invisibility. This kind of stuff happens a lot.
Easy fix: remove the SL invisibility potion and let us use the old ones (smirk)
Still no Expeditionary Boots on Exile's Reach... :(
Please Blizzard, fix the "We lost all of our health stones because our Warlock died and ran back, causing him to be > 40 yards from us" bug.
It's also pretty clear the original coders didn't leave a lot of good notes.