@RedWesty 

What's your app version? Please make sure it is up-to-date. Then you may refer to the suggestion below to do some troubleshooting.

Turn off the camera, remove and re-insert the SD card several times. Then turn on the camera and check if the SD card could be recognized.

If the SD card could be recognized by the computer, please try to format it to FAT32 on the computer. After that, insert the SD card into the camera again for a check.

It’s also suggested to test the card with third-party software such as MyDiskTest and here is more suggestion to verify an SD card.
https://www.tp-link.com/support/faq/2592/

@Stella.Q 

My App version is 2.2.7, the latest at this point in time. (April 2020)

I have done the turn it off and on again test, countless times, without success. Also remove and re-insert it. Still not being recognised though.

As mentioned in my original post the card has been checked and formatted to FAT32 and still not recognised by the camera.

I did as you suggested and followed your link, I downloaded the disk checker and let it do it's thing.

The disk shows no errors and is proved not to be a fake too.

Still not recognised by the camera, which suggests to me that it is in fact the camera that is faulty, not either of the brand new Scandisk SD cards.

As originally stated, the SD card worked fine for a while until the camera decided to not recognise it!

How do I go about getting a refund plaese?