An article in Recycling Today quotes speakers at WasteExpo 2018 identifying recycling problems:

The value of commodities recovered at material recovery facilities (MRFs) does not cover the costs to process these materials, and continual changes in consumer packaging don’t help.
"Brands are innovating their products’ packaging without a concern for the waste stream," said speaker Steve Alexander, president of the Association of Plastic Recyclers (APR). "They continue to push product innovations without testing if a specific product is recyclable. In many instances, brands don’t realize the pump in their bottle is not recyclable or that the ink on the packaging bleeds.
For all materials, there’s no requirement for design. It doesn’t have to be compatible with the infrastructure we have in place, and that’s a huge disconnect."
He added, referencing consumer packaging companies, "You’re innovating your packaging far quicker than we can tell residents how to sort it."