Interactive Service Hub-Merging Cases option not appearing

Hi,

I am trying to merge two or more active cases in Interactive Service hub but the option is not available. I can select cases by cheking them on the right and when I click "More Options" image(...) I only get Add to Queue option. Not sure why this is happening. We are currently on version 8.0 and it could be related. It will be helpful to get some explanation.

Thanks,

Nishant