Another user reported a MetaMask problem yesterday: https://support.mozilla.org/questions/1434630. ''I'll paste my reply here:'' I assume it's this extension, and some reviews indicate problems, although it's not a storm of posts: https://addons.mozilla.org/en-US/firefox/addon/ether-metamask/reviews/ Because money is involved, I suggest trying the most official support channel the author makes available, but also checking other sites for background.