I just received my ring today and tried storing a simple text string to the rear tag, which gave no errors when writing. Now when I try to read from or write to the rear tag I just get "Error: Tag is invalid". I have had no issues reading or writing to the front tag. I have a Samsung Galaxy S6 Edge and tried using the "NFC Ring Control" and "NXP TagWriter" apps and both have the same issue with the rear tag. I have no issues using the rear tag to unlock the phone, which is weird. I just get the same popup error as above every time I use it to unlock. Anyone else had this issue?