Hello,
I would like to thank everyone for their suggestions here. I was using Chrome + Evernote Web Clipper on Yosemite, but recently switched over to Safari. I also encountered some of the ancillary issues mentioned here about the Safari clipper not working; not loading, whether CSP was the issue, etc.
I wanted to briefly share my experience, in case someone else benefits from it.
I sometimes clip emails from Gmail into Evernote. On my first attempt, I received the "spinning wheel of nothing." I reloaded the page, and tried again. Same thing. I reloaded the tab, enabled