All Bills in the Bill approval workflow are created on behalf of a user called "Xero Requester". This user is notified about all key events: approvals, rejections, comments.
common reason for the Xero Requester to not get any notifications is that
the profile setup for him was not completed because he didn't accept an invitation. ApprovalMax only notifies users who were invited to the system and accepted the invitation.
Please follow these simple steps to fix the problem:
Log out from ApprovalMax (assuming that you are logged in under your email address).