Call alert is getting disappeared after every 20 minutes and reappearing after few seconds delay - SAP CRM BCM Cctr

Dear Experts,

Something strange happening during the incoming call...

When the call comes IN the alert disappears after every 20 seconds and the alert count start from the beginning after few seconds delay after every 20 sec however CDT it shows the exact time the customer is waiting (in alert).

Please find the attached screenshots from SAP CRM and CDT. Kindly suggest.

Thanks

Rahaman