Sigma wasn't expecting for her to be blown from where she stood. She is trying her best to create her playstyle of not moving from where she stood and unleashing abilities without doing much walking. All her life, she was in her wheelchair due to her unexplained sickness. With the help of her brother and the countless research of her father, she managed to at least alleviate her sickness and mitigate whatever was causing it.
Her father suggested that she should try to practice walking by practicing in the Virtual Reality game called Alternate World. She easily managed to get the Nexus Tattoo without a problem, allowing her to gain a 100% synchronization rate with herself and the character.
This is a pretty short arc to be honest since this is just a filler arc to fill some plot points and to also build up some parts that will lead us to the next arc. The next arc might be a long arc so I will just say this is the arc that serves as a break point to the next plot point. Thank you for reading this far.