Sergeant Garza Why?

Ok so I built my 55 floor and it was Security Hut- meaning I unlocked Sergeant Garza’s character. I have not unlocked a new character in quite sometime and I was excited to have her join my building and give me missions, like all the other characters do. Well so far that has not happened and I have had the building for ~ 5 days. I have not received a single mission from her but have been getting them consistently from my other characters still. Does anyone know what I going on or had this issue? TIA