We’re unable to validate your product’s purchase date.

I got my apple 8 plus from a telco in september 2018. I wanted to validate the warranty in March 2019 and tried doing so in https://checkcoverage.apple.com, when tried to look up my IMEI/serial number, i was surprised to see the following message "we’re unable to validate your product’s purchase date."

I reached out to apple support to sort this out, initially i was told that the device is under warranty but my concern was why this cannot be validated online. So the support agent assured that there might be an admin gap between the telco and apple and this will be sorted once i submit the contract details which i did. After which, i had to follow up again with a call to support on the status, during which time i was told that i will have to take back up of my phone and restore phone using itunes, after this is done, the warranty information will get updated within 72 hours. I've done the backup and restore process last night, i will know whether it worked or not come friday.