A custom Vendor Certification has been added for the OLD-CISCO-TS-MIB to gather data on the metric:
What you need to do is set the metric expression. Without a metric expression set, then nothing is collected.
DX NetOps CAPM 20.2 or later
Go to the Vendor Certification (VC) and select the metric currently not being collected that you wish to gather data for. In this case example, select the Cisco Serial Interface VC and scroll down till you see themetric then click on 'Edit':
Then, set the tsLineNses metric expression to itself:
Then accept the expression and save. After this Go to the device, and under Polled Metric Families, select the Alternate Interface and hit the "Update Metric Family" button to rediscover.
You should now see the metric being collected: