Check session returns login required auth0lock

Calling checkSession occasionally returns -
error: “login_required”, error_description: “Login required”
This error occurred once on our team’s dev server but did not occur when testing on localhost.

This is how I am calling check session:
const options = {
auth: {
redirect: false,
responseType: ‘token id_token’,
rememberLastLogin: false,
},
nonce: “1234”,
};
lock.checkSession({options}, function(err, authResult) {
if (err || !authResult) {
console.log(err);
}
else {
const accessToken = JSON.stringify(authResult);

}

Previous forum posts related to this that suggest changing cookie settings etc. have not resolved the issue. Any help would be appreciated!