I found OpBot on a room and was decided to hire him, I proceed to dismiss one of my heroes 4 heroes which happens to be on the same room, after that I wasn't able to interact and hire OpBot. It could be another cause but it's the only thing I can relate to.



So, found a hero, ignored it to dismiss one of my own, lead to never be able to interact (get the dialog screen) and hire the recently found hero.



EDIT: I've replicated the issue and didn't happen, so that is not the cause, but it happens!