Filter Gallery is greyed out in Photoshop

Hi everyone! So, my filter gallery *used* to work. But, now, it does not and has not for a very long time. But today, I really need it. Yes, yes, yes. I've tried every single fix in this thread, yet nothing has restored my filter gallery. While I tend to agree with one of the comments that Photoshop needs to get with the program in terms of archaic structure, below are the solutions that I have tried (though I shouldn't have to try so hard!):

1. confirmed RGB color mode is set to 8 bits

2. File is not too big - 1920x1080, 300 dpi (in fact, filter gallery does not work in ANY file, no matter how small or large)

3. Filter gallery is enabled (is not greyed out)

4. PS is up to date

5. Tried closing re-opening about 9,000 times sime this has been ocurring

5. Copied layers into a new doc, to no avail

So, what gives, PS folks? I dunno. I'm thinking, a bug??? Totally annoying for the flipping subscription fee we all pay, knowing there are SO many other competitors with uh, more inutitive features.

Any magic would be appreciated. 🙂

I had the same issue with an RGB, 8 bit file.  For me, the problem was the file was too big for the filter gallery to recognize.  My file was 120" x 80" and I had to reduce the image size to 90"x 60" and the filter gallery choice became enabled.

I am having the same issue. Everything I have tried has not worked!

If the size of image is very big fiter won't work. My reseloution was 600 I reduced it to 300 and started to work

Posting in case anyone else like me finds this from Google and the answers here aren't helping you: 
In addition to a file being in 16bit or CMYK, another issue can be the file dimensions. One of the other answers here mentioned PSB vs PSD, but that's not the issue, the file size can be as big as can be, what matters are the dimensions. If your file is over 30,000px then certain filters will be greyed out. (I haven't tested if they're the same ones that are greyed out for being in 16bit but I'd assume so). 
Bonus tip, if you're wondering why "Lens Blur" is greyed out for smart objects, who knows, but it can be re-enabled. Photoshop used to come with a sample script to "enable all filters" but it's no longer included, but you can find it by downloading the Scripting Listener plug in: https://helpx.adobe.com/photoshop/kb/downloadable-plugins-and-content.html

I changed it to Image-Mode-RGB-8bits and it works.

Hi, I'm having the same issues as described below (using Photoshop v 21.1.1.) on Mac Catalina. My tif or jpg images are in RGB 8 bit, small in size (600 px at 72 dpi), layer is unlocked. I've reset Preferences, have quit Photoshop and reopened a number of times. The filter gallery does not, will not, apply to this or to any other images. Please help. Thank you!

I have the same issue and it's driving me crazy. I've tried RAW files, JPG's, it's all in 8 Bit, and no matter what I try, (and reopened Photoshop several times) the depth channel will not appear. Using PS 2020.

It could also be greyed out if your document is too big, so that it can only be saved as a PSB, not PSD