I believe this is a bug. To replicate:
- Write a post (question or answer)
- Insert an image and choose to provide it from your computer. Click on the banner to open the file selector and select an image and choose OK (do not drag and drop).
- You should see a preview.
- Click on
Cancel and add another image
- Attempt to add the same image, again with with file selector. No preview, no option to add it (button remains disabled)
Tried in IE 11 and Chrome 54.
Attempted with .png and .jpg images
The console in dev tools only shows 1 failure of
Please note, I keep editing the steps to improve clarity based upon feedback from comments, as such, comments may be out of date