If I have an email account hosted on a 3rd party service and I add a new mail account to my Zoho Mail as an IMAP account, should all the custom additional folders that exist in the original mail account sync across to Zoho MAIL account?

On having done this I found that Inbox, Sent Items and Drafts sync'd however other folders at same level as Inbox plus a sub folder of Inbox have not sync'd or have only partially sync'd. The IMAP account was set up a week ago. Is this something that just takes a great deal of time? I do have a lot of emails to sync even if onloy restricted to all those since Jan 2021