Emails older than 1 day suddenly disappear on Outlook 365 (release 16.0.17328.20142) online mode

Hi folks

since a few days now, our colleagues reported that often and all of a sudden, emails older than 1 day disappear from a shared Online Mailbox.

Once this occurs, they click on another folder and then go back again to Inbox and the emails show up again.

We have deployed the latest available Outlook 365 version (release 16.0.17328.20142) but issue still occurs.

This happens to all users accessing that shared mailbox. Also, it occurs on multi devices.

Are we the only ones facing this issue ?

Kindly advise

D