The only real documentation on this is buried in a WWDC19 video, because Apple can't be bothered to provide decent canonical documentation:
https://developer.apple.com/videos/play/wwdc2019/717/
jeffhunterx
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The Extensions tab of Safari preferences is an absolute clown show. In previous versions of macOS, there have been bugs where it is possible to enable an extension via the keyboard, but the mouse does not work. (See apple dot stackexchange dot com question 214760, because these forums won't allow me to include a link.)
Now the "solution" to this problem on Catalina is to "Make sure that your extension preferences pane is frontmost in the middle of your screen with no other windows covering any of it."
This is ridiculous. Can someone from Apple please explain why it is necessary to have a bunch of hacks that *do not work* in the Safari extension preferences? What exactly is being defended against here, and how is it worth these bizarre bugs that cause our customers to just assume that Safari and our extensions are broken?
I found a way to consistently reproduce this on iOS 14.4.1. If I go to a certain URL (which I would post, but the developer forum software will not allow it), then my sharing action in Safari doesn't show up the first time you open the share sheet, but does show up the second time you open it. This URL has an anchor on the end of it (i.e., it ends with a hash symbol followed by some text).
If I got to the same URL with the anchor removed from the end of it, my sharing action shows up the first time I open the share sheet.
I have filed FB8889913.
Yes, we are seeing the same problem after app updates. Many of our users have to restart their devices to see our extension. These problems have been going on since iOS 14.0 was released. They never happened on iOS 13.x. I have filed FB8889913 and FB9045442 and have been hoping with each 14.x release that it will be fixed, but it still happens on 14.4.1.
I filed FB9045442 about this, and now Feedback Assistant says "Resolution: Potential fix identified - In iOS 15".