I know this question has come up before, but none of the answers have helped me unstick this problem. I have created a filter, but I don't see any way to share it. Sharing isn't an option under the dot menu:

Under the "Details" menu, there is an "Edit permissions" link:

But on the dialog that comes up, I can't actually share the filter:

I checked the global permissions, and it does appear that I have permission to share dashboards and filters -- in fact, I granted this permission to everyone. Any idea what I'm doing wrong?