Are you viewing in Unified mode? Try: View > Folders > All or Menu icon > Folders > All

If this does not correct the situation Check Account Settings: Tools > Account Settings or right click on mail account name in folder Pane and select 'Settings'

Select 'Copies & Folders' for the mail account.

If POP: select 'Place a copy in' Select 'Sent folder on' and mail account name.

IF IMAP select 'Place a copy in' Select 'Other' and Sent folder on mail account name.

If Imap and gmail: Do not select the following as gmail will auto put it in the gmail Sent folder. uncheck: 'Place a copy in'

Do that for each mail account. click on 'OK' to save and close Account Settings.

Thanks Toad-Hall, the POP account was giving me grief and updating the settings fixed it. Have a great day. Regards. Marg MargRoy said

I have about 6 email addresses and have unique Inbox and Sent folders for each address. As of a few days ago my Sent emails no longer drop into the individual sent folders, I can only access them from the higher level of Sent. Ideally I want to retain sent emails unique to each email address. Appreciate any assistance. Regards Marg