Outlook 365 Driving me mad

Hi Newbie here.

I have Microsoft Office 365 and I am trying to use Outlook on my laptop operating on Window 11.

Up until now I have used BT on the web. However it's very slow so thought I'd use Outlook on my laptop. But I have an infuriating problem.

When I send from Outlook on the laptop there is no copy sent to the sent folder. The emails are sent to recipients and received.

When I send from either BT on the web or my BT phone App the message is is saved in the sent folder there and also in Outlook's sent folder.

I have seen the fixes and in options, as all say, I have the save copy of the email ticked. But it refuses to play ball.

I have two accounts for Office 365 but irrespective of which I am signed into the problem persist.

Can some one please help?

Many thanks

Since you have set
then I suggest you run an Office repair.
Support and Recovery Assistant for Office 365
Repair an Office application - MSSupport


Best of luck,
Denis