LogShipping Alert Job on Secondary server is failing with no backup msg.

Hi,

The Log shipping alert job on secondary server is getting failed and giving the error below.

'The log shipping primary database --------- has backup threshold of 60 minutes and has not performed a backup log operation for 166653 minutes. Check agent log and logshipping monitor information. [SQLSTATE 42000] (Error 14420).  The step failed.'

When I have a look at the table log_shipping_monitor_primary from two different servers, the records on primary server
are showing the last_backup_date as the recent one but from the secondary server, the last_backup_date is about 4 months back.
And hence the error shows 'has not performed a backup log operation for 166653 minutes'.

What can be the possible reason for the error in the 'LogShipping Alert Job on Secondary server' and how to resolve?

Thanks