Hey, @Sophie1988 .
I’m sorry to hear you’re also having trouble with your products appearing. If you’ve gone through all of the possibilities I’d mentioned above, this may be due to how your products are pulled onto your store. It is also odd that they sometimes appear after a period of time.
I wanted to confirm with you, what are the steps you go through when adding a product, and then including it in a collection?
Thank you!
Lizzy