Hi Mohammed,
Thank you for your feedback. Now we understand that your tenant has not been upgraded.
According to this situation, I would like to confirm if the same issue occurs to Outlook desktop client.
Moreover, please capture a screenshot of your OWA page and post it in this thread.
I’ve found the following article for your reference. Please refer to it and check if there is anything incorrect with your on-premises configuration.
Configuring On-premises Lync Server 2013 Integration with Exchange Online
Regards,
Allen Zhang