Add Product to Collection, Save, See it in Collection, Refresh the Page, Product Disappears

Hi - I’ve seen this asked a few times when searching and usually a Shopify Guru asks to reach out direct.

I have a few products that just won’t stick in any collections. I add them from the Collections Page and I also try adding from the Product Page. It looks like it works but after saving and visiting the page, it mysteriously disappears from the collection. Only happening with a few new products from what I can see.

Just after saving:

After Refreshing:

Hi, I figured it out and posting reply here in case anyone else comes across this thread via Search.

We had created some collections in the regular Shopify Admin Panel and some collections in the app Smart Metadata Collections. The Smart Metadata Collections was the culprit re-moving items, seemingly at random, across all our Collections regardless of collection creation origination. Not sure if just a buggy app or what but once I deleted, all was good.