Sent emails from an account with neither Imap nor Pop aren’t shown in “sent all”.
If you have an SMTP only account, so you have disabled IMAP, then the sent messages should only be on the server, and as eM Client is not syncing the server folders by IMAP, there is nothing to show.
What you can do in that instance is to create a Rule to move all messages sent through that account, to another Sent folder in eM Client, where you can see them.
So like this:
