I think the problems are that:
1. This product is designed for use on a rotary polisher.
2. It uses diminishing abrasives which means you need to make sure that you work it long enough.
3. It requires follow up with a finishing polish.
From Autogeek's Store description:
"Meguiars Diamond Cut Compound #85 2.0 is fast-cutting compound for paint correction and swirl removal. Use #85 with your rotary polisher to level severe scratches and defects on automotive paints with a high solids content, such as those used by Mercedes and Ford. Diamond Cut Compound is low dusting and leaves minimal swirls.
Meguiars Diamond Cut Compound #85 2.0 rates a 10 on Meguiars scale of cutting power. It uses diminishing abrasive technology to level sanding scratches and severe paint defects using your rotary polisher. Yet, because the abrasives gradually disappear, this compound finishes with only light swirls, which can be easily removed with a finishing polish.
Meguiars Diamond Cut Compound #85 2.0 is recommended for rotary use. Its professional quality formula is designed for the high speed cutting that can only be provided by a circular/rotary buffer. For heavy oxidation and severe sanding scratches, use an 8.5 wool pad. Follow up with Meguiars #83 Dual Action Cleaner Polish and an orange pad to polish the paint to a high gloss."
I suggest you switch to M105 which is compatible with DA and rotary.