Layer Mask keeps creating transparent areas

[HuzzaCreative]

As you can see in the photo, after I apply my layer mask, it Photoshop seems to be creating these transparent areas around the edges. How can I get rid of these or what settings are causing this?

[HuzzaCreative]

So I figured out how to fix it, but I'd still like to know why it keeps doing this. If anyone ever encounters this problem in the future, you need to right click the Mask in the layer, and then click "Mask Options" and turn the contrast all the way up. Not sure if it works for all situations, but it works for this specific time.

[Bojan Živković]

There's nothing wrong here, nothing is perfect, and often, additional effort is needed to achieve the selection you want. The Select and Mask workspace provides other tools to help refine your mask.

A small amount of feathering along the edge isn't necessarily a bad thing, as it can help the object blend with the background, if one is present. You're in control of how much feathering is applied, which is why Photoshop offers a variety of tools and options for working with selections and masks.

[Chuck Uebele]

How were you creating your selection to make you mask, in the first place. a lot of the automatic selections are just a good start and often need tweeking like you did here.

[HuzzaCreative]

I started with a "Isolate Object" (I think that's the term? or select subject)". Then it selected what I wanted and more.

So then I had to manually go and + and - with the lasso tool what I wanted. From there I contracted, expanded, feathered, smoothed, re-selected a few times. I get that feather has something to do with it but it doesn't make sense to just feather these few sections, especially after I made changes.

[Trevor.Dennis]

What you are probably doing is adding a Layer mask to the Background layer.  When you do this, there is nothing below that layer, so it shows as transparent.

If the checkerboard upsets your view of the image, simply add a new layer below the layer with the mask, and fill it with white.

[barbara_a]

If you describe the steps and tools you are using I may be able to pinpoint the resason why it is happening.