Hi Andrew,
Any chance you might be on flakey internet when it is not working? I believe I once saw this same thing a long time ago, and thought it had something to do with resources not fully downloading or the browser cache referring to some older version of one of the resource files.
Regarding multiple shares, I was referring to Create a copy and then sharing the copy. Glad to hear it is working now. If you notice anything that is consistent about the times you see this happen let us know and we will try to track it down.
Two things to try which might tell us if it is the internet connection.
- Try holding down the shift key and reloading the browser page. Then try sharing again.
- Open an incognito window and then load the doc to see if the sharing dialog is working.
If either of those work to consistently fix the sharing dialog issue. It is likely incomplete resource download (or some browser caching issue).