Export all lastpass passwords, including hidden. If you're sick of lastpass failing to fill inputs properly, just paste this in the console on the extension vault page.

export.js

var q, p = ['Username', 'Password', 'URL'], m = LPProxy.getAllModelItems(), o = [];
for(var i in m){
    q = [];
    for(var j in p) q.push([p[j], m[i]['get' + p[j]]()].join(': '));
    o.push(q.join('<br/>'));
}
window.location.href="data:text/html;charset=utf-8," + escape(o.join('<hr/>'));