Unable to choose file in ANY browser

I'm having a really strange problem that I'm unable to figure out. If I'm trying to choose a file to upload, after selecting the file in the popup file explorer then selecting Open, I get "No file chosen". It's as if I selected no file at all. I can keep repeating this selection and the site doesn't recognize that I've chosen a file to upload. It happens on any site where you can upload a file, in any browser. I've tried Firefox, Chrome, and Edge. I'm guessing there is something going on with Windows Explorer/File Explorer.

For testing, I'm using this: File Upload Test

I don't have any programs modifying Windows Explorer like ClassicShell, etc.

I've already run:
sfc /scannow
DISM /Online /Cleanup-Image /RestoreHealth
chkdsk C: /f
Disk Cleanup to clean Thumbnails
Folder Options > Clear File Explorer history
Folder Options > Reset Folders

All Windows updates are installed.

www.oac.uci.edu’s DNS address could not be found.

Click to expand...

The error message says it is not the correct upload address. Confirm the upload address.

Can you upload an attachment to this Forum?

Spunk said:

The error message says it is not the correct upload address. Confirm the upload address.

Can you upload an attachment to this Forum?

Click to expand...

I see what you're saying once you click upload. The site is only a test site, doesn't matter which site it is on. It happens on every site where you can upload a file. Selecting a file through the file explorer pop up doesn't actually select anything. It will still say "No file chosen" after selecting the file and pressing "Open".

Same thing happens here and on other websites.