Thanks for the question.

Whether it is Aster Yellow or mites, it is too early to make a conclusive decision.  This is probably why you have received conflicting answers from other sources.  I am struck by how healthy the foliage looks. For the time being, this would argue against Aster Yellow. We would urge your continual monitoring of the situation.

To provide you some background information, both diseases have three similarities:

1). Both need an insect to carry infection from an infected plant to an uninfected plant.

2). Both cause deformations in coneflower flowers.

3). Remedial treatment is the same for both diseases.

Both diseases have four differences:

1). In aster yellow the actual causative organism is a type of bacteria. With coneflower rosette mites, the actual causative organism is a virus.

2). The transmitting insect with aster yellow is a leaf hopper. With coneflower rosette disease, it is an eriophyid mite.

3). There is no chemical treatment for aster yellow, and the disease will eventually lead to the death of the plant.

4). There is no chemical treatment for coneflower rosette disease, but usually the deformed plant survives.

See the following for further information and to use as a checklist in the monitoring of your plants:

https://extension.umd.edu/resource/aster-yellows-disease-flowers/

https://bygl.osu.edu/node/2191

https://extension.umn.edu/plant-diseases/aster-yellows

https://www.walterreeves.com/landscaping/coneflower-aster-yellows-vs-coneflower-rosette-mite/

https://gardenerspath.com/how-to/disease-and-pests/aster-yellows/

If you wanted to be proactive, consider submitting plant samples to a diagnostic disease laboratory for an analysis. This would be a definitive way to arrive at a decisive answer to your question. Both Wisconsin and Minnesota have excellent labs to do this. Before submitting anything to either of them, call first as to what type of samples should be submitted. Both have a nominal charge for their analysis. See:

https://pdc.umn.edu/

https://pddc.wisc.edu/clinic-overview/

Good luck. Please keep us apprised of your situation as we will be glad to answer any further questions that might arise.

Glad to be of assistance.  Thanks for consulting us.