Shared list between personal and business - sync not working

Hello everyone

I recently asked myself if it is possible to share a ToDo list between a personal and business account. Well, I found on this page that it is possible but only when the personal account is the owner of the list and shares it with a business account. So, I tried it by myself and I got it to work but not as good as I hoped.

I can join the list with my business account but when I add a task it won't sync it and doesn't show up in the list on the personal account. Bizarrely when I add a task from the personal account side it syncs the task, and It will be shown on my side with the business account.

I tried it with personal to personal account as well and this one works perfectly...

Thanks for your responses.