Outlook (2019 Desktop) with 2 accounts. does not add tasks from 2nd account to todo list

Hi,

I use Outlook 2019 with 2 email accounts from 2 domain (a + b).

My to-do list wast maintained in account a and I used it successfully for number of years to manage tasks for a and b.

Recently, the contents of the to-do list disappeared .. it seems that the todo list is maintained in account b and I can only add tasks from account b to the todo list.

Can anyone advise how to revert to the pervious scenario .. where todo list was maintained in a and I an add tasks from a and b to the to do list?

Thank you

john