Outlook 365 desktop has ceased to update btinternet IMAP folders automatically for no apparent reason. No settings had been changed when this started and remain as given on the btinternet page. I would assume this is something to do with the last monthly Microsoft update, except that a colleague who also uses btinternet mail for home use has had exactly the same problem for more than a week: on opening, the Outlook status bar reports 'Connected', but nothing happens, and even a manual Send/Receive All Folders does not synchronise the folders. About 30 minutes or so after opening, it sometimes does start to download new messages, and intermittently thereafter, but since it can be seen on both iPhone (using Outlook) and webmail (using Edge) that new email has been received but not updated on Outlook desktop, Outlook desktop is obviously not reliably updating and synchronising as before. There is advice elsewhere to ensure the setting Folder tab> IMAP Folders > "When displaying hierarchy in Outlook, show only subscribed folders" is unchecked, so I have unchecked it (though it was previously checked without any lack of synchronisation anyway), but this has had no effect on the problem. My PC has Windows10 Home and Microsoft 365 with automatic updates, so always the most up to date versions of everything. Can anyone advise if this is a current BTinternet issue?
I use Outlook 365 on two email addresses and calendars and it all seems to work as normal (with a desktop, laptop, two iPhones and an iPad all syncing. Occasionally I have to click Refresh and rarely I get a Connect button showing.