So I've encountered this issue twice now so I'm going to write this post just to reach out to see if anyone else has encountered it and see if it's becoming an common issue... (or an intentional secret mechanic? LOL)
Essentially, Nex Vera launches a large radius blast attack upon reaching enraged status (stage two). This attack then has a follow-up attack which is a targeted blast attack as opposed to a general blast. However, it has happened a second time now that the second follow-up blast has been cancelled. You would think that, because the first blast has occurred that Nex would just continue as normal... This is not the case. Later on in the fight, Nex will restart the entire attack for a second time. The first time this happened, it was cancelled by an elemental down. The second time it happened, Nex simply decided to adapt a different fight pattern before promptly restarting the blast attack.
So yeah, has anyone else encountered this because... I don't think it's supposed to work like that.