Banding issues in Camera RAW

Okay! I think I've got it sorted! D Fosse put me on the right path.

I updated my drivers, ACR, and turned off Graphic Processing in ACR preferences, but none of that did anything. I had to adjust my Color Management on my computer in order to get it to look alright. Looks great now! Thanks everyone!

From the screenshot, this looks like excessive black clipping, with different clipping points in the three channels (hence the banding). This is a common symptom of a defective monitor profile. On Windows, this is the most likely explanation (but incidentally, this is how the MacOS/Lightroom issue looked also).

ACR is a special case because the data are converted from linear ProPhoto into the monitor profile. This is a more complex conversion than that from a standard working space profile.

There seems to be a lot of information here that you have to watch the full video to get.

Are you on Mac? Something along those lines happened with Lightroom 4 and 5 after a certain Mac OS version (can't recall which). It turned out to be Apple dropping legacy support for certain APIs or frameworks. No other option than upgrade or roll back OS. I assume the corresponding ACR versions would be similarly affected.

It's a lot easier if you just post screenshots BTW.

Until our color management expert D Fosse​ comes along, here are a couple of suggestions.

First, try to disable the GPU in Camera Raw in preferences (press Ctrl+K while in Camera Raw). Uncheck Use graphics processor.

Second, you seem to be using Monitor RGB as your working space - this is not something you should do, as it disables color management. Set it to a standard profile like Adobe RGB or sRGB, and set Color Management Policies for RGB to Preserve embedded profiles. Photoshop will display the image correctly even if the profiles don't match, and unnecessary profile conversions should be avoided, since you may be throwing away color information that cannot be retrieved once the conversion has happened.