Event invites going to wrong calendar

I've seen one similar issue and no solution.

My wife and I both have both iPhones and MacBooks using apple Calendar app as default. We each have our own calendars. They are set up in iCloud. They are both shared with each other as view only.

I have also set up a second calendar, in my iCloud account, for our dog. This is also shared with my wife with edit permission.

If I make an event and invite my wife to it, she gets the invite in her (only) calendar.

If my wife makes an event and she invites me to it, it goes to my dog calendar. I have tried every setting under the sun to change this but it still goes to the dog calendar. My personal calendar is my default calendar in all of iPhone, Mac, and iCloud settings. In iCloud, invites to new events are set to my personal calendar. Still invites go to the dog calendar.

If I delete the dog calendar, event invites go to my personal calendar (my only calendar).

If I create another calendar, called 'Test 2', event invites go to Test 2 calendar.

If I create another calendar, called 'Test 3', event invites go to Test 3 calendar. For clarity, in this scenario, I have three calendars and invites go to the most recently created calendar.

All of this strikes me as buggy behaviour as nothing seems to be respecting settings.

Please advise on how I can select for event invites to come to my preferred calendar?