The apple has an issue w it's core.
Unfortunately, your photos did not come through. I am unable to say whether this is the correct course of action. If a soil test shows a calcium deficiency, then spraying with calcium will correct the issue.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/calcium-fertilizer.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-and-calcium.htm
https://www.gardeningknowhow.com/edible/fruits/apples/growing-honeycrisp-apple-trees.htm
Not all the apples are affected. We covered the apples in mid June with small mesh bags to prevent bugs. Have looked at many websites but have not seen photos that look like our apples. We hope you can help us. We live in central Montana. Had 7 inches of rain in June. Tree is watered with Thank you.
This looks to be black rot and requires control rather than treatment. A fungicide wouldn't hurt, though. Here is an article that will help:
https://www.gardeningknowhow.com/edible/fruits/apples/black-rot-on-apple-trees.htm