Quote Originally Posted by dbltoe View Post
Just to bring all up to date....

I deleted all line items with a value of 0 in the options_id field of the products_attributes table of the database.

All is fine now.
I have just noticed the same thing.

I added some attributes to a few products and it triggered the same warning.

And yes, a couple of the products have options_id of 0 attached.

The products investigated were added in 2020. I can't think of anything 'different' I would have done - but one theory is that these products are a copy of another and I would have used the then version of 'multiple product copy' to do this.