Andrew posted this article on random occasions Google has denied the Google Shopping ads for retailers that abide by all rules. Since I do not have a Facebook ID I will make my comments here.
We noticed a problem last week and it was more severe than Product Ads being disapproved. Only the products with "approved" Product Ads were actually searchable in Google Shopping. Only 934 of our 6652 products could be found using a generic search in Google Shopping despite the Merchant Center saying that all of the products were searchable. Removing the products from Product Ads seems to have fixed the problem.
Here is part of Andrew’s article.
A few hours ago we received word that on random occasions Google has denied the Google Shopping ads for retailers that abide by all rules. These retailers were given no notice on why their Google Shopping ads were disapproved, just a nasty looking graph in the Google Merchant Center: