There are a lot of threads here already that explain the how and the why - it's not magic, a crap shoot or anything else, it's simply that some phones do not work as well as other phones and that your method is going to affect how well it functions far more than you realise. You're learning to do something new. Do it slowly, work out where and how you get it to happen consistently and that means checking the entire back of your phone again with the ring oriented first one way and then the other - horizontal and vertical. Slowly! There may be a few 'sweet spots' and some may work better or worse than others. Practice does make perfect.

If you're absolutely positively unable to make it read properly and consistently after spending some time on it then you may need to change to an Alpha ring, assuming yours is the normal classic ring.

To finish off, this is not other NFC products. Your other NFC products are not made of metal and aren't in a ring - this changes dramatically how it functions and what the read distance is going to be like. You cannot go into this assuming it will behave like an NFC fob, forget that and start from scratch, go slowly and try everything, I can't emphasise that more.