New install, "Upload files" button nonfunctional

[DaveZ]

New install - completely new - up to date version.

Upload Files button does not work in Content Manager or File Manager. In File Manager, it just doesn't do anything. In Content Manager, it lets me choose a folder, but won't let me choose and upload a file.

I can drag and drop but I'm working with other people and I think it'll be a mess if we have to use File Manager, drag and drop images, then go back and work with them in Content Manager.

Any ideas? Using Safari 14 on Mac Mojave (10.14.6).

[DIGI3]

Does it work in other browsers? Does anything show in the javascript console?

If it doesn't work in other browsers, and especially if there's a 403 or similar error in the console, my best guess would be mod_security. If you don't have the ability to disable it in your hosting control panel, ask your host if they can disable it or whitelist the rule in question.

[DaveZ]

It was only in Safari - Firefox works. Surprised I didn't check that before messing around with ModSecure!

No console error - just doesn't work - weird.

[DIGI3]

I just tested in Safari 13.1 on Mac and it worked properly, so you might have to narrow it down before filing a bug report:
-clear the browser cache and/or try a private window
-do you have any popup blockers or other plugins that could be interfering?
-can you recreate it on another computer with the same browser (use browserstack.com or similar if you don't have another system to try)

If you can make the problem happen reliably on other systems, make a note of the browser and OS version here so others can verify.

[DaveZ]

Oops. Popup blocker. Built into Safari. ... wait, it was off.
All cookies and such removed, rebooted... no change.
I'll go with "local issue" though - thanks!