After spending many hours replicating this issue on various monsters in various situations. I've done the math and your chain abilities will only grant a successful chain towards your next chain ability 86% of the time. Leaving your successful hits a 14% chance to fail in granting your progression towards your next chain ability. At first it seemed as though I were missing, causing me to not gain access to my next ability chain. But it became clear rather quickly that this was not the case. This happens regardless if class or the enemy engaged. There is just too great of frequency for failed chain abilities to not need a fix. Trying to Tank can be extremely frustrating for everyone in the group, because you rely on these chains to be 100% successful for aggro purposes. You have a very short window to gain a sustainable amount of aggro and require a successful hit with your third chained ability to achieve this. The combat in this game evolves around chaining abilities, it's the core of the combat. With this not working and your chains not connecting, the core of the combat breaks. Please don't ignore this.