Players not getting game time can disrupt a harmonious squad. Leicester currently have 4 strikers barely getting any minutes so unless they're perfect professionals they could be causing a problem. He's probably on big wages as well, they might want to free up squad space for a new signing, the manager might not rate him. Plenty of possible reasons.
They have loads of strikers - Iheanacho, Vardy, Okazaki, Ulloa, Slimani, Musa. Surely they could spare Slimani.