Accessibility selection rectangle is not appearing at the second instance of the interactive object.

Hi, 

I have created added the customozied progress bar for interactive video slides. I have added the accessbility text for all the buttons in the progress bar (image attached below). When I press tab key, selection rectangle is moving based on the tab order assigned.  Using the space bar, I muted the audio of the interactive slide. 

My question is when I would like to trun on audio that time selection rectangle is not going back to 'mute' button, I don't know why. If I turn off mute button using selection rectangale, it should be possible to turn on using selection rectangle, right? 

But, when the selection rectangle is in the same place that time it is possible for me to turn on audio. However, after turning off mute button and brought selection rectangle to some other button, I am not able to bring that selection rectangle again to the mute button to turn on audio. Please guide me.