Navigate by row - rotor setting

Hi, I'm currently into a mission about investigating how deafblinds people can use VO with IOS. I'm also testing apps from a accessible perspective. My question is about the rotor in VO. Some of the deafblinds people does need to navigate by row. But it seems to be a possibliity that depends of not only where the cursor are located but also which app you are running. That makes me think this is a coding issue rather than a VO issue. Does anyone know more about this? /Thomas