Adjustment Brush "Painting" Black

You are most welcome - RP

Again, this is just Lightroom doing what you have told it to do. The radial filter is applying your current default settings, in the first instance.

The new filter is lightening (instead of darkening) the area defined by the mask, because of having changed the Exposure value (if fresh adjustments are showing this now, you must have done so without any adjustment being selected), It is also continuing to reduce contrast and reduce saturation; those defaults are unchanged.

(Oh, and are you asking why the radial filter's mask is applying outside the oval area, rather than inside? That is one of the Radial filter's settings (you'll probably need to scroll to the bottom of the panel to see it). Click on "Invert Mask" to switch between outside and inside.)

It is likely that what you are remembering from before, are some prior local adjustment defaults which initially applied no adjustment at all - rather than, as now, applying a very visible adjustment straight away.

To get back to that earlier situation, simply select one of the tools (say, radial filter) and immediately before doing anything else, set all the adjustment sliders to zero - do this BEFORE clicking on the image. Now whenever you do click on the image hereafter, each fresh adjustment that you place, will begin by doing nothing visible to the image - until you change that particular adjustment's sliders to something different.

Your default local settings have been set to reduced Exposure and reduced Contrast, and reduced Saturation.

This is the effect of moving sliders around while you have got nothing selected. You just update what starting settings will get used the NEXT time you start brushing a new local adjustment, also the NEXT time you start a new radial or graduated filter.

You are going to continue to see these same settings as your starting point, unless you maybe change them to something else. But a particular local adjustment can be given different settings of its own, and will then individually remember those / allow those to be further altered.

Try this: with the image in the state shown in the screenshot, change the Exposure to a higher value. The image should change accordingly. Now click New above the local sliders, and place a new radial filter onto a different part of the photo. See what Exposure is saying. Now click on the pin of the first radial adjustment again. See what Exposure is saying now. Hopefully this will make it clearer to you what is going on. This is all LR working quite normally.

Ah, OK. (apologies for misunderstanding your aim here).  Could be this:

In your screenshot just after writing "It's like after i use the adjustment brush, the area is left black no matter what settings I adjust (contrast, exposure, etc.)..." you show some sliders which you say make no difference to the adjustment which has been applied.

At the top of the adjustment sliders area, are buttons "New" and "Edit". "Edit" is not highlighted in your screenshot. This indicates that you do not at this time have ANY adjustment pin selected.

This is the normal condition each time you go back to using this tool. But in your screenshot showing the green mask overlay, the pin IS clicked (has a black centre). So in that state, the adjustment sliders DO change the settings for this particular mask.

LR does not know until you tell it, whether you now want to begin a brand new 'pin', or alter the settings / change the brushing for an existing 'pin' - and if there are several of those, which 'pin' you mean.

To re-access the settings for a mask that has previously been painted on, and also in order to paint / erase its mask differently, you will need to have clicked on the "pin" that was originally placed on the image, as the first action in doing that.

(In the event that you don't see existing pin(s) on opening the adjustment brush tool, those may have been set as visible "Never". Press T to open the toolbar, change the pins' visibility there to either Auto or Always.)

As wobertc mentioned you have 'Show Selected Overlay Mask' checked and set for Green color. Select one of the Adjustment Brush pins and hit the O key to turn it off. Hit 'Reset' in the Adjustment Brush panel and start over. This is only used to show where the mask is applied and NOT something that is applied to the image. You can use the 'Color' panel at the bottom of the Adjustment Brush panel to add a Green hue color to the image along with other settings to achieve the desired effect.

Lauren, the screenshot you posted shows the Spot Removal tool (see below). Perhaps you applied it by mistake and then tried using the Adjustment Brush?

Try this. With the posted image file selected click on the Spot Removal tool and then click on its 'Reset' as shown below.