Steps to reproduce:

In v115, there is no means provided for mailboxes to be polled individually, unlike prior versions which allowed the user to poll only one mailbox rather than the entire list of mailboxes.

Actual results:

Individual mailbox polling was apparently removed in v115.

Expected results:

The user should be able to poll individual mailboxes if so needed, rather than need to poll the entire mailbox list.

You can still do it via right-click (context menu) in the folder pane header.