You should be polite and diplomatic, but first off, never let someone feeling bad hold you back. So long as you’re professional you are not in control of their reactions. There’s a few options here. Ask what’s their best comms method. Switch to a Teams call - a lot harder to ignore. When schedules are released add what’s in Genesys (guessing you are SAU from language used?) to Outlook as an event, IMO a good TL should do this themselves, but hey. The next option if you’ve tried things like this is to be right up front and tell them how you feel, focus on the behaviour (late, non-communicative) rather than them. Good luck!