Problems using Add To Radial/Gradient Adjustment Brush in Adobe Camera Raw

I created a radial adjustment in Adobe Camera Raw. I selected the brush tool to modify the area impacted by the adjustment. This has worked in the past. However this time, the add to selection brush did NOT operate properly, and it has not since. The add to brush seems to apply in an ABSOLUTE LEVEL. So, where ever the add to the radial adjustment brush is applied, the local adjustment goes to some uniform level. What used to happen is that where ever the add to brush was applied, the adjustment would increase up to a 100% of what ever the radial adjustment was (gradually or immediately depending on the flow setting of the add to adjustment brush). My guess is that I inadvertently hit some setting shortcut. HELP!

Other info:

-- The add to the radial adjustment brush seems to work fine when used outside the area impacted by the radial adjustment.

-- The erase/subtract from the area impacted by the radial adjustment seems to work fine.

-- The same issue occurs when trying to use the brush to modify a gradient adjustment.