This happened before the sync limit had been reached. I figured out that a Web clipper was considered "a device", despite it being used on the same computer as one of my other devices.
I found a workaround. One, I uninstalled EN on a computer and only use it on the web on the second computer.
Two, You can disconnect from the internet then close and reopen Evernote. It doesn't lock you out.
Three, best workaround - I've ditched evernote. This policy pissed me off and I've decided they're not worth keeping.