@AEMLearner-1989 I would suggest posting this question in Sites community, rather than Assets. You will get a faster response: https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/ct-p/adobe-experience-manager-community 

@srikanth7792 you have correctly mentioned the OOTB feature in your post, more info described in Adobe doc: https://experienceleague.adobe.com/docs/experience-manager-64/assets/administer/metadata-import-export.html?lang=en Can you please elaborate more on the specific custom requirement?  

As discussed, here's the solution: the metadata headers were not marked in individual columns. Please mark this answer correct @harsingh

Please checkout this related thread: https://experienceleaguecommunities.adobe.com/t5/adobe-experience-manager/overlay-clientlibs/qaq-p/183703 

Can you please share the sample file so that I can test? you can inbox me.

@chetan001 You first need to configure Brand Portal publish setup as described here: https://experienceleague.adobe.com/docs/experience-manager-cloud-service/assets/brand-portal/configure-aem-assets-with-brand-portal.html?lang=enBy default, the assets will only be published to the default publisher ...

@harsingh91 I faced this issue once, as the file extension was causing confusion for AEM.There are multiple extensions available while saving the updated CSV file, make sure you check carefully and retry upload.  If you still face any issues, refer to this help doc for header info: https://experienc...

you can simply paste the smart tag in AEM OOTB search bar and hit enter. You will see all the results containing that specific tag.Shortcut: / + Enter 

I suggest raising a support ticket with Adobe Daycare team. They should be able to check the URL inconsistencies and provide a working sandbox. 

@khamat_bn @Please check the workflow status from Tools>Workflow>InstancesTerminate any stuck workflows and try uploading the file again.Hope this helps.