Pinterest Rich Pins stopped working for most of the pins from my site

We had Rich Pins enabled for our Pinterest business account half a year ago. It's all working good for our site from which all kinds of pins are correctly displaying the price and title at the top of the pin page on Pinterest.com.

It suddenly stopped working recently with NO price NOR title being displayed for maybe 95% of our pins (BUT not all), either new ones just created today or ones that used to have the price and the big title, such as these:

https://www.pinterest.com/pin/92394229835498920/
https://www.pinterest.com/pin/92394229834399749/
https://www.pinterest.com/pin/92394229834382263/

If you click through the pins to our product page and inspect the page source and you will see that the og (Open Graph) variables are all in place in the head of the page.

When we run the Rich Pins validator against our product pages like this: https://developers.pinterest.com/too...blue-sash.html

It keeps giving this error:

We have no idea what that means. We thought maybe Pinterest couldn't access our site but when we examined our server logs, it seemed Pinterest had successfully fetched our pages no problem at all:

This is really weird.

Nonetheless even weirder is that some (very few) of our pins DO work, like this one:

https://www.pinterest.com/pin/92394229834334208/

You can see the price and the big title above the pinned image are correctly showing up. This doesn't make sense since all our product pages share a common template. Why is it that some pins work but others don't?

I tried to reach Pinterest support but it's not so helpful as of now.

I have absolutely tried everything up to my sleeve but nothing good thus far. Any help or clue would be tremendously appreciated! What am I missing here?