Can you share the custom code here?

visid_high and visid_low values are retrieved from svi cookies while ECID value (mcvisid_high/low) are derived from AMCV cookies. It would make more sense to compare the post_visid_high/low values to compare the data when using ECID values.  

If you are not setting Page Name in processing rules, the server calls from the app need to be checked. I would advise reaching out to Customer Care for further help.

You can go to Components > Scheduled Projects, select the Project from the list and hit "Delete" button.

Okay. I did not realized you already reached out to Customer Care. I would suggest posting the query to https://experienceleaguecommunities.adobe.com/t5/adobe-analytics-ideas/idb-p/adobe-analytics-ideas. This forum is used by the product team to capture feedbacks from customers and implement new fea...

I you are trying to ingest data from S3, there is no out-of-the-box feature. However, you may use Bulk Data Insertion API.

Try using Visits (All Visitors) metric in Data Warehouse.

I would suggest contacting Customer Care with the details of the request (endpoint/body/headers) so that this can be checked internally.

Rule Builder runs every four hours. If the classification files are found empty (after you upload the file) and it falls within the "overwrite window", the Rules Builder will update new value as per the rules. 

You can capture Campaign IDs in any of the evars/props. You just need to set pup your code to set the variable.