I had stopped using the Voidwalker/Voidlord pet because of lack of threat generation. It was useless. In fact, I noticed the other day that I had >1,000,000% threat (vs. Voidlord) on a mob in Zereth Mortis when I tried him again.
Then I realized I had Glyph of Voidlord on all my specs. As a test I tried the Voidlord one last time and still could not hold aggro. I removed the Glyph and resummoned as a Voidwalker and low and behold he was able to hold agro even with me blasting away.
Has any one else seen this issue where the Glyph is altering threat generation?