I had the same problem happen a few times.. it seems to happen randomly (or, at least, I have not found any sure way to reproduce the bug). The only solution I found is to reload the page. Here's the Javascript error that Firefox shows when I try to either double-click on the token or click on the gear icon to open its settings. Error: Permission denied to access property "nodeName" in base.js:55:2526 Hopefully, that might help you narrow down the origin of the problem?