Sorry for the late reaction, we very recently migrated our website and Forum and we still need to do some serious fine tuning … working on that.
I do not think the HUB was defective, i am quite sure you had a Bandwidth issue.
A displayport 1.2 output has 21.7Gbps of bandwidth. When running 1 screen in 1920x1080p in 144Hz in 8Bpp the signal is 8.96Gbps big. Using 2 you got o 17.92, needless to say that a third will need more Bandwidth that you have available …