Legion General invisible and invincible - 897.823.393

Hey there,

As the title says, I've encountered a Legion General (Viper Napuatzi) that is both invisible and invincible after succesfully breaking her out and the legion starting.
I'm in T16 Defiled Cathedral.
Running Legion Astrolabe currently on third stage, having three buffs:
- Legion duration
- Legion pack size
- Legion sergeants rewards

The image shows me hovering over the Legion General (mouse is not visible on screenshot, but I marked the area in the picture).
https://imgur.com/a/HkPpo05
In the chat you can also see that she did her voice line which she does when succesfully breaking her out. But she cleary isn't there (also aoe / brands do not damage / attach to her).
She was visible but invincible right after breaking out. Then I went to clear the other side of the Legion and when I came back she was now invisible. I did not break out the other General.