A calendar invitation gives a conversation a place but cannot supply its purpose.

Booking a slot solves the logistics and none of the substance. A time and a room say when people will be in the same place, which feels like progress, but the question of what the conversation is actually for stays unanswered until somebody answers it. Half the meetings that go badly were never given a purpose, only a start time.

Before you send the next invitation, write one sentence saying what will be different afterwards. If you cannot write it, the meeting is not ready. If you receive one without it, asking politely what the aim is will be a favour to everybody attending.